Add "How to Run WinterCMS Documentation Locally"

[Satoshi-Sh]

Updates

Added a guide on how to run WinterCMS Documentaion site for contributors.

This PR needs to add the instruction on how to add required theme(doc) and plugin(winterdoc)

Some errors

While testing, I encountered the following errors. The documentaion is working fine.

I don't know those errors are important or not.

[bennothommo]

@Satoshi-Sh, I think this could be better integrated into the Development section that's already part of the README instead of just being a list dump of commands.

As for the errors - that'd be coming from the Search plugin. When did those errors appear - which command were you running at the time?

[Satoshi-Sh]

@bennothommo Thanks for the feedback, I moved the instruction into the Development section.

I got those errors when I ran php artisan doc:process. Probably, I need to configure the search plugin?

[LukeTowers]

@bennothommo I know I've run into those issues myself before, is there something missing from the search plugin or am I just not setting it up correctly?

[bennothommo]

@Satoshi-Sh @LukeTowers those DBs are created (using the ArraySource trait) when you generate indexes for the docs, but that's done as part of the docs:process action, so I can only assume it's some sort of race condition where the indexes are being queried before they're being generated.