doc: fix nits in tools/doc/README.md

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

doc, tools

• Sync format schemes with the current doc state.
• Lowercase primitive types.
• Fix typos and unify the style.
• Remove tautological info.