doc: fix api docs style
Summary
doc/api/async_hooks.md
- L198: Missing code-language flag
- L239: Missing code-language flag
- L317: Missing code-language flag
- L347: Missing code-language flag
doc/api/fs.md
- L2857: Unused definition
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
commit message follows commit guidelines
Affected core subsystem(s)
doc