add trait@, union@, value@, macro@

text/1946-intra-rustdoc-links.md

@@ -300,16 +300,28 @@ Our proposal is this:
     e.g., `See [type@foo]`.
   - Links to modules can be prefixed with `mod@`,
     e.g., `See [mod@foo]`.
+  - Links to traits can be prefixed with `trait@`,
+    e.g., `See [trait@foo]`.
+  - Links to unions can be prefixed with `union@`,
+    e.g., `See [union@foo]`.
+  - It does not actually matter which disambiguator you use, so you can also
+    just use `type@foo` for all type-namespace objects
+    (structs, enums, types, mods, traits, unions)
 - In links to macros,
   the link label _must_ end with a `!`,
-  e.g., `Look at the [FOO!] macro`.
+  e.g., `Look at the [FOO!] macro`. You can alternatively use a `foo@` prefix,
+  e.g. `[macro@foo]`
 - For disambiguating links to values, we differentiate three cases:
+  - Links to any kind of value can be prefixed with `value@`,
+    e.g., `See [value@foo]`.
   - Links to functions can be written with a `()` suffix,
     e.g., `Also see the [foo()] function`.
   - Links to constants are prefixed with `const@`,
     e.g., `As defined in [const@FOO].`
   - Links to statics are prefixed with `static@`,
     e.g., `See [static@FOO]`.
+  - Again, it does not matter which disambiguator gets used, provided it
+    is in the value namespace (const, static, functions)
 
 For disambiguation markers using an `@`, in implied shortcut links
 you can use a space instead of the `@`. In other words, `[struct Foo]`