Change install cmd to always update sshcode

Author: nhooyr

README.md

@@ -23,7 +23,7 @@ Chrome is recommended.
 Install with `go`:
 
 ```bash
-go get go.coder.com/sshcode
+go get -u go.coder.com/sshcode
 ```
 
 Or, grab a [pre-built binary](https://github.com/codercom/sshcode/releases).
@@ -68,4 +68,4 @@ export VSCODE_EXTENSIONS_DIR="$HOME/.vscode-insiders/extensions"
 
 By default, VS Code changes on the remote server won't be synced back
 when the connection closes. To synchronize back to local when the connection ends,
-pass the `-b` flag.
+pass the `-b` flag.