Documentation of --compilation.commands_dir is wrong

[saraedum]

--compilation.commands_dir arg the directory where a
compile_commands.json is located, its
options have lower priority than the
other ones

However, the compile_commands.json does take preference, see https://github.com/standardese/standardese/blob/master/tool/generator.cpp#L36.

We should change the documentation to clarify that.

[matthijskooijman]

I just ran into this. Maybe it could be considered to change the implementation to match the documentation instead?

My usecase is documenting some embedded code that contains a check against the gcc version macros. For clangd, I have solved this with -fgnuc-version=10.0.0, which works in addition to the flags from the compilation database. For standardese, passing this option by itself works as expected, but once I use a compilation database it is ignored. Similarly -D options are ignored then, so that doesn't help me either...