Modernize the README slightly

[RyanGlScott]

• Mention version 3, not 2, of Cryptol. This fixes Version 2 -> Version 3 #1542
• Modernize the copyright years slightly
• Mention significant contributions from @qsctr, @Riib11, and @m-yac

[weaversa]

Woo!

I think there is potential for improvement in the Where to Look Next section. But that's all I see left.

[RyanGlScott]

I think there is potential for improvement in the Where to Look Next section. But that's all I see left.

Are you referring to this sentence?

cryptol/README.md

Lines 181 to 182 in 57226ef

	If you are familiar with version 1 of Cryptol, you should read the
	`Version2Changes` document in the `docs` directory.

That is, would you like to see any accompanying document for changes between Cryptol 2 and 3?

[weaversa]

I think there is potential for improvement in the Where to Look Next section. But that's all I see left.

Are you referring to this sentence?

cryptol/README.md

Lines 181 to 182 in 57226ef

	If you are familiar with version 1 of Cryptol, you should read the
	`Version2Changes` document in the `docs` directory.

That is, would you like to see any accompanying document for changes between Cryptol 2 and 3?

That's the sentence. There was support for the move from 1 -> 2...it would be nice to have a Version3Changes, similar to the existing Version2Changes. Also, adjacent documentation also needs to be updated, for example, the syntax guide doesn't mention the new module system.

[yav]

I think we may want to remove the "syntax guide". All the stuff in it should be in the reference manual---I used the syntax guide as the starting point for the reference manual.

[RyanGlScott]

Because these are larger changes (and I don't want to hold up the rest of this PR on them), I have opened separate issues to track the remaining documentation suggestions:

• Remove the syntax guide: docs: Fold the syntax guide into the reference manual #1545
• Add Version3Changes: docs: Create Version3Changes to describe syntax changes between Cryptol 2 and 3 #1546