Add support for additional extensions

[ldore]

Mintlify seems to detect the language from the file extension.
But some languages are not restricted to a single extension.

For example:

• cpp is correctly detected for the .cpp file extension...
• ... but other acceptable file extensions for c++ are not recognized:
  • Source files: .c++, .cc and .cxx.
  • Header files: .h++, .hh, .hxx and .hpp
  • https://stackoverflow.com/questions/5171502/c-vs-cc-vs-cpp-vs-hpp-vs-h-vs-cxx mentions additional, less common extensions (.ii, .ixx, .ipp, .inl for inline definitions, .txx, .tpp and .tpl for templates...)

It would be great if those extensions were supported. (Or if additional custom extension/language associations could be added in the settings).