Fix Doxygen warnings

[pjonsson]

The \c and \b commands accept a single word,
and there are no \section1 or \list commands
according to the Doxygen manual.

[pjonsson]

Even with this patch, I still get a pile of warnings in doxygen.log that I'm not sure how to fix.

tinycbor/src/cbor.dox:74: warning: Documentation for undefined enum 'CborType' found.
tinycbor/src/cbor.dox:94: warning: Documentation for undefined enum 'CborKnownTags' found.
tinycbor/src/cborerrorstrings.c:32: warning: Documentation for undefined enum 'CborError' found.
tinycbor/src/cborpretty.c:136: warning: Documentation for undefined enum 'CborPrettyFlags' found.
tinycbor/src/cbortojson.c:669: warning: Documentation for undefined enum 'CborToJsonFlags' found.
tinycbor/src/cborvalidation.c:55: warning: Documentation for undefined enum 'CborValidationFlags' found.
tinycbor/src/cborparser_dup_string.c:87: warning: unable to resolve reference to 'CborErrorOutOfMemory' for \ref command
tinycbor/src/cborparser_dup_string.c:56: warning: unable to resolve reference to 'CborErrorOutOfMemory' for \ref command
tinycbor/src/cborparser.c:957: warning: unable to resolve reference to 'CborErrorDataTooLarge' for \ref command
tinycbor/src/cborparser.c:1273: warning: unable to resolve reference to 'CborErrorOutOfMemory' for \ref command
tinycbor/src/cborparser.c:1236: warning: unable to resolve reference to 'CborErrorOutOfMemory' for \ref command
tinycbor/src/cborparser.c:1357: warning: unable to resolve reference to 'CborErrorDataTooLarge' for \ref command
tinycbor/src/cborparser.c:1384: warning: unable to resolve reference to 'CborErrorDataTooLarge' for \ref command
tinycbor/src/cborparser.c:936: warning: unable to resolve reference to 'CborErrorDataTooLarge' for \ref command
tinycbor/src/cborparser.c:642: warning: unable to resolve reference to 'CborInvalidType' for \ref command
tinycbor/src/cborparser.c:1400: warning: unable to resolve reference to 'CborInvalidType' for \ref command
tinycbor/src/cborpretty.c:564: warning: unable to resolve reference to 'CborPrettyFlags' for \ref command

[thiagomacieira]

\list is probably a qdoc'ism, but I thought I had fixed the issues long ago.

[pjonsson]

I know the Doxygen in Ubuntu 18.04 has a lot fewer warnings than the Doxygen in Ubuntu 20.04 and 22.04. The CI seems to use Xenial (16.04), so I guess that is even more permissive.

If you're not already aware, my experience is that Doxygen breaks ENABLE_PREPROCESSING with PREDEFINED between patch releases. It worked for me with the Doxygen in Ubuntu 18.04, and is broken in Doxygen 1.9.1 which is what comes with Ubuntu 22.04. The issue is fixed in Doxygen 1.9.4, and 1.9.5 breaks the support again.