Add a `cd` to proxy build instructions (#40065). Remove an unnecessary `go get` from client build instructions.

home.md

@@ -58,6 +58,7 @@ There is now an ansible role to install a Snowflake proxy on Debian [created by
    ```
 3. Build the Snowflake proxy.
    ```
+   cd snowflake/proxy
    go build
    ```
 4. Run the Snowflake proxy.
@@ -76,7 +77,6 @@ The following should result in a 100% bootstrap over WebRTC:
 ```
 git clone https://git.torproject.org/pluggable-transports/snowflake.git
 cd snowflake/client
-go get
 go build
 tor -f torrc
 ```