This commit mostly just fixes compilation errors when compiling in C++20 mode, though the change to std::filesystem::path::u8string()'s return type means it's not backwards-compatible with C++17.
- The string encoding and errors sections move to the reference page
- The metadata files section moves to the introduction page
- The language codes section is already detailed in a C++ header doc comment
- The caching section is already detailed in C++ header doc comments
- The performance section is outdated and isn't worth keeping once updated.
- The string encoding and errors sections move to the reference page
- The metadata files section moves to the introduction page
- The language codes section is already detailed in a C++ header doc comment
- The caching section is already detailed in C++ header doc comments
- The performance section is outdated and isn't worth keeping once updated.
Oliver Hamlet