Port user guide pages from wiki

[starkos]

What does this PR do?

Port all of the user guide content from the wiki to the new website.

How does this PR change Premake's behavior?

Website only, no code changes.

Anything else we should know?

There is still more to do before taking the site live; see #1547.

Did you check all the boxes?

• Focus on a single fix or feature; remove any unrelated formatting or code changes
• Add unit tests showing fix or feature works; all tests pass
• Mention any related issues (put closes #XXXX in comment to auto-close issue when PR is merged)
• Follow our coding conventions
• Minimize the number of commits

You can now support Premake on our OpenCollective. Your contributions help us spend more time responding to requests like these!

[KyrietS]

EDIT: In my previous comment I said that using [text](name-of-file) instead of [text](Name-Of-File.md) won't give us warnings about broken links. But it's not true: https://v2.docusaurus.io/docs/docusaurus.config.js/#onbrokenlinks. Sorry for that.

All looks great. Just one little thing. We still have many warnings about broken links.

A few examples:

• in Home.md there is broken link to What's-New-in-5.0.md.
• in Command-Line-Arguments.md there is Adding-a-new-Action instead of Adding-New-Action.
• many broken links in Lua-Library-Additions. Most of them are to the files I deleted as they were auto-generated without sensible content.

run npm run build to see all warnings.

For CI job I'd like to change onBrokenLinks: 'warn' to onBrokenLinks: 'throw' so every version of our website is going to have no broken links.

[starkos]

I guess I misunderstood how/when broken links were reported. I've now run npm run build and fix all issues, and I also added a note to README.md for future developers. If I don't hear otherwise I'll go ahead and merge this later today.

For CI job I'd like to change onBrokenLinks: 'warn' to onBrokenLinks: 'throw'

Yes, definitely.

[KyrietS]

Warnings about broken markdown links (e.g. [text](Some-File.md)) are reported in dev mode when you run npm start. But raw links, like [text](some/relative/path) are checked during build process only.

Now it looks good to me 👍

[starkos]

Thanks for the review. Merging now, and then I'll get started on the index and download landing pages.