[clang-doc] static member variables are not included

[danakj]

Some examples:

struct i16 final {
  static constexpr auto MIN_PRIMITIVE = __private::min_value<PrimitiveT>();
  static constexpr auto MAX_PRIMITIVE = __private::max_value<PrimitiveT>();
};

There's no reference to these members in the i16 docs.

Whereas hdoc at the moment doesn't generate any of the methods, but it does include the static member variables: https://docs.hdoc.io/danakj/subspace/r8A877CC61EAA03B1.html

# Member Variables
public int16_t primitive_value = {0}
public static const auto MIN_PRIMITIVE = <recovery-expr>(__private::min_value<short>)
public static const auto MAX_PRIMITIVE = <recovery-expr>(__private::max_value<short>)
public static const sus::num::i16 MIN
public static const sus::num::i16 MAX
public static const sus::num::u32 BITS

My command line in case it helps: ../llvm/build/install/bin/clang-doc --project-name=Subspace --format=html --output=docs --extra-arg=-Wno-error --repository=https://github.com/chromium/subspace/blob/main --public -p out compile_commands.json --executor=all-TUs

Here's an example in action: https://danakj.github.io/subspace-docs/sus/num/i32.html