- Documentation for `bufferevent_compat.h` and `rpc.h` is not generated
since the `@file` command is missing. It can be fixed by adding
`@file` in file comment block.
- The briefs of buffer.h,bufferevent.h and some other files are missing.
Adding `@brief` command can fix it.
- The parameters in the function declaration are different from the
parameters following the `@param` command.We should change them to the
same.
- Documentation of `watch.h` is not generated since `watch.h` has not
been added to the Doxyfile `INPUT` tag.
- Add link to the watch.h in event.h
