Add pat_param to follow set restrictions.

Author: ehuss

src/macros-by-example.md

@@ -28,7 +28,7 @@
 >
 > _MacroFragSpec_ :\
 >       `block` | `expr` | `ident` | `item` | `lifetime` | `literal`\
->    | `meta` | `pat` | `pat_param`  | `path` | `stmt` | `tt` | `ty` | `vis`
+>    | `meta` | `pat` | `pat_param` | `path` | `stmt` | `tt` | `ty` | `vis`
 >
 > _MacroRepSep_ :\
 > &nbsp;&nbsp; [_Token_]<sub>_except delimiters and repetition operators_</sub>
@@ -451,7 +451,7 @@ Matchers like `$i:expr,` or `$i:expr;` would be legal, however, because `,` and
 `;` are legal expression separators. The specific rules are:
 
   * `expr` and `stmt` may only be followed by one of: `=>`, `,`, or `;`.
-  * `pat` may only be followed by one of: `=>`, `,`, `=`, `|`, `if`, or `in`.
+  * `pat` and `pat_param` may only be followed by one of: `=>`, `,`, `=`, `|`, `if`, or `in`.
   * `path` and `ty` may only be followed by one of: `=>`, `,`, `=`, `|`, `;`,
     `:`, `>`, `>>`, `[`, `{`, `as`, `where`, or a macro variable of `block`
     fragment specifier.