docs: update local development docs (#8573)

* bump some program versions to latest stable

* use powershell syntax highlight

* use one sentence per line

* Python 3.8.7 is latest stable...

* remove version output of PowerShell commands

* use less descriptive text to see versions in use

* add definite article the

* make the text more specific

* rewrite 2 sentences

* rewrite part of the keeping fork up to date section

* use a list, add introductory sentence

* rewrite adding configuration options section

* split debugging into 2 parts, rewrite text for both

Co-authored-by: Rhys Arkins <rhys@arkins.net>