Various fixes to C# documentation

(cherry picked from commit 2deabd5)

modules/mono/glue/GodotSharp/GodotSharp/Core/Mathf.cs

@@ -651,7 +651,7 @@ public static int StepDecimals(real_t step)
         /// </summary>
         /// <param name="s">The value to stepify.</param>
         /// <param name="step">The step size to snap to.</param>
-        /// <returns></returns>
+        /// <returns>The snapped value.</returns>
         public static real_t Stepify(real_t s, real_t step)
         {
             if (step != 0f)

modules/mono/glue/GodotSharp/GodotSharp/Core/MathfEx.cs

@@ -44,7 +44,7 @@ public static int DecimalCount(real_t s)
         /// <summary>
         /// Returns the amount of digits after the decimal place.
         /// </summary>
-        /// <param name="s">The input <see cref="decimal"/> value.</param>
+        /// <param name="s">The input <see langword="decimal"/> value.</param>
         /// <returns>The amount of digits.</returns>
         public static int DecimalCount(decimal s)
         {
@@ -54,7 +54,7 @@ public static int DecimalCount(decimal s)
         /// <summary>
         /// Rounds <paramref name="s"/> upward (towards positive infinity).
         ///
-        /// This is the same as <see cref="Ceil(real_t)"/>, but returns an <c>int</c>.
+        /// This is the same as <see cref="Ceil(real_t)"/>, but returns an <see langword="int"/>.
         /// </summary>
         /// <param name="s">The number to ceil.</param>
         /// <returns>The smallest whole number that is not less than <paramref name="s"/>.</returns>
@@ -66,7 +66,7 @@ public static int CeilToInt(real_t s)
         /// <summary>
         /// Rounds <paramref name="s"/> downward (towards negative infinity).
         ///
-        /// This is the same as <see cref="Floor(real_t)"/>, but returns an <c>int</c>.
+        /// This is the same as <see cref="Floor(real_t)"/>, but returns an <see langword="int"/>.
         /// </summary>
         /// <param name="s">The number to floor.</param>
         /// <returns>The largest whole number that is not more than <paramref name="s"/>.</returns>
@@ -78,7 +78,7 @@ public static int FloorToInt(real_t s)
         /// <summary>
         /// Rounds <paramref name="s"/> to the nearest whole number.
         ///
-        /// This is the same as <see cref="Round(real_t)"/>, but returns an <c>int</c>.
+        /// This is the same as <see cref="Round(real_t)"/>, but returns an <see langword="int"/>.
         /// </summary>
         /// <param name="s">The number to round.</param>
         /// <returns>The rounded number.</returns>

modules/mono/glue/GodotSharp/GodotSharp/Core/NodePath.cs

@@ -130,7 +130,7 @@ public NodePath() : this(string.Empty) { }
         /// "/root/Level/Path2D"
         /// </code>
         /// </example>
-        /// <param name="path"></param>
+        /// <param name="path">A string that represents a path in a scene tree.</param>
         public NodePath(string path)
         {
             ptr = godot_icall_NodePath_Ctor(path);

modules/mono/glue/GodotSharp/GodotSharp/Core/StringExtensions.cs

@@ -423,6 +423,10 @@ public static string Extension(this string instance)
         /// <summary>
         /// Find the first occurrence of a substring. Optionally, the search starting position can be passed.
         /// </summary>
+        /// <seealso cref="Find(string, char, int, bool)"/>
+        /// <seealso cref="FindLast(string, string, bool)"/>
+        /// <seealso cref="FindLast(string, string, int, bool)"/>
+        /// <seealso cref="FindN(string, string, int)"/>
         /// <param name="instance">The string that will be searched.</param>
         /// <param name="what">The substring to find.</param>
         /// <param name="from">The search starting position.</param>

modules/mono/glue/GodotSharp/GodotSharp/Core/Transform.cs

@@ -164,7 +164,7 @@ public Transform Inverse()
         /// Operations take place in global space.
         /// </summary>
         /// <param name="target">The object to look at.</param>
-        /// <param name="up">The relative up direction</param>
+        /// <param name="up">The relative up direction.</param>
         /// <returns>The resulting transform.</returns>
         public Transform LookingAt(Vector3 target, Vector3 up)
         {

modules/mono/glue/GodotSharp/GodotSharp/Core/Transform2D.cs

@@ -23,7 +23,6 @@ public struct Transform2D : IEquatable<Transform2D>
         /// <summary>
         /// The basis matrix's X vector (column 0). Equivalent to array index <c>[0]</c>.
         /// </summary>
-        /// <value></value>
         public Vector2 x;
 
         /// <summary>
@@ -420,12 +419,12 @@ public Transform2D(Vector2 xAxis, Vector2 yAxis, Vector2 originPos)
         /// Constructs a transformation matrix from the given components.
         /// Arguments are named such that xy is equal to calling x.y
         /// </summary>
-        /// <param name="xx">The X component of the X column vector, accessed via <c>t.x.x</c> or <c>[0][0]</c></param>
-        /// <param name="xy">The Y component of the X column vector, accessed via <c>t.x.y</c> or <c>[0][1]</c></param>
-        /// <param name="yx">The X component of the Y column vector, accessed via <c>t.y.x</c> or <c>[1][0]</c></param>
-        /// <param name="yy">The Y component of the Y column vector, accessed via <c>t.y.y</c> or <c>[1][1]</c></param>
-        /// <param name="ox">The X component of the origin vector, accessed via <c>t.origin.x</c> or <c>[2][0]</c></param>
-        /// <param name="oy">The Y component of the origin vector, accessed via <c>t.origin.y</c> or <c>[2][1]</c></param>
+        /// <param name="xx">The X component of the X column vector, accessed via <c>t.x.x</c> or <c>[0][0]</c>.</param>
+        /// <param name="xy">The Y component of the X column vector, accessed via <c>t.x.y</c> or <c>[0][1]</c>.</param>
+        /// <param name="yx">The X component of the Y column vector, accessed via <c>t.y.x</c> or <c>[1][0]</c>.</param>
+        /// <param name="yy">The Y component of the Y column vector, accessed via <c>t.y.y</c> or <c>[1][1]</c>.</param>
+        /// <param name="ox">The X component of the origin vector, accessed via <c>t.origin.x</c> or <c>[2][0]</c>.</param>
+        /// <param name="oy">The Y component of the origin vector, accessed via <c>t.origin.y</c> or <c>[2][1]</c>.</param>
         public Transform2D(real_t xx, real_t xy, real_t yx, real_t yy, real_t ox, real_t oy)
         {
             x = new Vector2(xx, xy);