grammar/README.md is outdated

[est31]

src/grammar/README.md is outdated. First, it still contains mentions of the legacy make system. Also, while make and make tidy technically might work, make check-build-lexer-verifier doesn't work at least since commit 9ab8090 and the claim that make tidy includes the check is wrong even longer (d3b050c).

It should be updated. Most likely the the checks have to be ported over to the new system as well.

[kennytm]

make and make tidy still works with rustbuild (the latter calls x.py test src/tools/tidy).

[est31]

@kennytm still, make check-build-lexer-verifier does not work (probably) since commit 9ab8090 and the claim the lexer verifier is built during make tidy is wrong even longer, since commit d3b050c .

The file is simply outdated and should be updated.

[est31]

I'll edit the description to fit the problems more closely.

[steveklabnik]

Grammar stuff is in the reference now; we should remove the stuff in-tree.

[est31]

In fact the file in question was removed by commit c3781e6 (PR #41705). There's still grammar stuff in tree but that should be tracked by a separate issue. Closing.