Adds option to install plugin with branch name

[arabnejad]

[arabnejad]

closed by b6ceb79

I added the branch input arg when we run install_plugin task

fabsim localhost install_plugin:<plugin_name>[,branch="<branch_name>"]

[djgroen]

Same for this one: did you add this option to the documentation as well?

[arabnejad]

The instruction is added to https://fabsim3.readthedocs.io/en/latest/plugins.html