man std::vector,how/where does it search for corresponding documents internally?
man(1) man page:
SEARCH PATH FOR MANUAL PAGES man uses a sophisticated method of finding manual page files, based on the invocation options and environment variables, the /etc/man.config configuration file, and some built in conventions and heuristics. First of all, when the name argument to man contains a slash (/), man assumes it is a file specification itself, and there is no searching involved. But in the normal case where name doesn’t contain a slash, man searches a variety of directories for a file that could be a manual page for the topic named.
There's a lot more text in there though. I'll let you read it at your leisure.