Update documentation on how to install extensions

[nichjones1]

Is your enhancement related to a problem? Please describe

The current documentation does not reflect the details on how to install extensios

Describe the solution you'd like

Update existing documentation to include details on how to install extensions

Describe alternatives you've considered

No response

Additional context

No response

[cdrage]

Notes from Tim and I:

• Update the current "installing extensions" page with screenshots
• Move installation extensions page higher up on the side-bar so it's more showable
• Rename extensions folder to something else (writing extensions is not useful, maybe development extensions)