Merge pull request doxygen#12151 from albert-github/feature/bug_doc_ext_map

Incorrect formatting of "language" with `EXTENSION_MAPPING`

Author: doxygen

src/config.xml

@@ -670,7 +670,7 @@ Go to the <a href="commands.html">next</a> section or return to the
  Doxygen selects the parser to use depending on the extension of the files it parses.
  With this tag you can assign which parser to use for a given extension.
  Doxygen has a built-in mapping, but you can override or extend it using this tag.
- The format is <code>ext=language</code>, where \c ext is a file extension, and language is one of
+ The format is `ext=language`, where `ext` is a file extension, and `language` is one of
  the parsers supported by Doxygen: IDL, Java, JavaScript, Csharp (C#), C, C++, Lex, D, PHP,
  md (Markdown), Objective-C, Python, Slice, VHDL, Fortran (fixed format Fortran: FortranFixed,
  free formatted Fortran: FortranFree, unknown formatted Fortran: Fortran. In