detab GRAMMAR section
Remove V1 and V2
Sync grammar of `TraitsKeyword` (issue 11711 fix)
Sync and improve grammar of `LabelStatement`
Sync with grammar.dd
Use `opt` for arguments of CallExp
[bugfix] `ArrayLiteral` can have no arguments
Merge pull request #468 from 9rnsr/grammar

Sync grammer.dd and grammars in other pages