Add more documentation do Syntax nodes

[kimdv]

Part of #1528

I've started to add more documentation to the syntax nodes.
Some of them are pretty trivial and not sure if that is the path we want.

Like the effect specifiers, we could generate them if we wan't them.
I think they give some value specially places where we use asyncSpecifier etc. Here are two valid options.
We could generate

The `async` or `reasync` keyword.

Then they could be able to click on them and navigate to it.

When generating this, we could make rule, that if we define the documentation then it overrules the generated ones

[SimplyDanny]

Just a few suggestions from my side ...

[ahoppen]

Mostly looks good to me. Thanks @kimdv. I wonder if cases like

The `actor` keyword

can be handled as part of #1987

CC @natikgadzhi

[natikgadzhi]

@ahoppen @kimdv yep! I haven't jumped into #1987 fully yet, but it does feel like when a child has just one / few possible kinds or specific tokens — we could generate documentation on those automatically based on those kinds, without hard-coding the specific doc string for each child. Thank you for nudging me here! <3

[kimdv]

Mostly looks good to me. Thanks @kimdv. I wonder if cases like

The `actor` keyword

can be handled as part of #1987

CC @natikgadzhi

Will remove those cases again.
Then it can be handled in #1987.

[kimdv]

@ahoppen added more documentation.
Should we review and merge this or should I add more?

Can also add more in a separate PR if you want?

[ahoppen]

Yes, let’s merge this. Just looks like the change to CodeGeneration/Package.swift is unrelated.

[kimdv]

@swift-ci please test

[kimdv]

@swift-ci please test windows