Add a `cd` to proxy build instructions (https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40065). Remove an unnecessary `go get` from client build instructions.
Update markup. I could not find gitlab wiki pages for doc/PluggableTransports, doc/PluggableTransports/SnowFlakeEvaluation, doc/TorBrowser/Hacking, doc/Snowflake/Fingerprinting, and org/teams/AntiCensorshipTeam/SnowflakeBridgeSurvivalGuide, so I linked them back to trac.