Add default documentation for undocumented keybind actions

Previously, `ghostty +list-actions` would only show actions that had doc
comments, making it difficult for users to discover all available actions.
This change ensures all actions are listed with appropriate documentation.

For actions without doc comments, we now generate a default message
encouraging contribution.

src/helpgen.zig

@@ -115,6 +115,38 @@ fn genActions(alloc: std.mem.Allocator, writer: anytype) !void {
     try writer.writeAll("};\n");
 }
 
+fn genKeybindField(
+    alloc: std.mem.Allocator,
+    writer: anytype,
+    ast: std.zig.Ast,
+    comptime field: []const u8,
+) !void {
+    const tokens = ast.tokens.items(.tag);
+
+    // Find the field and check if it has doc comments
+    for (tokens, 0..) |token, i| {
+        if (token != .identifier) continue;
+        const name = ast.tokenSlice(@intCast(i));
+        if (!std.mem.eql(u8, name, field)) continue;
+
+        try writer.writeAll("pub const ");
+        try writer.writeAll(name);
+        try writer.writeAll(": [:0]const u8 = \n");
+
+        // If it has doc comments, use them
+        if (i > 0 and tokens[i - 1] == .doc_comment) {
+            const comment = try extractDocComments(alloc, ast, @intCast(i - 1), tokens);
+            try writer.writeAll(comment);
+        } else {
+            // Otherwise use default documentation
+            try writer.writeAll("    \\\\This action is currently undocumented.\n");
+            try writer.writeAll("    \\\\Please refer to the source code or contribute documentation.\n");
+            try writer.writeAll(";\n");
+        }
+        break;
+    }
+}
+
 fn genKeybindActions(alloc: std.mem.Allocator, writer: anytype) !void {
     var ast = try std.zig.Ast.parse(alloc, @embedFile("input/Binding.zig"), .zig);
     defer ast.deinit(alloc);
@@ -128,7 +160,7 @@ fn genKeybindActions(alloc: std.mem.Allocator, writer: anytype) !void {
 
     inline for (@typeInfo(KeybindAction).Union.fields) |field| {
         if (field.name[0] == '_') continue;
-        try genConfigField(alloc, writer, ast, field.name);
+        try genKeybindField(alloc, writer, ast, field.name);
     }
 
     try writer.writeAll("};\n");