Deletion of Recursive grammar

Comment: this easily meets the |general notability criteria. The concept is widely used in compiler design and also theories of human language. I have added several references with extended discussions of the concept
Stance: keep
Cited policy: Wikipedia:Notability (WP:GNG)

Comment: I ly removed "recursive grammar" from the formal languages template and rewrote the stub to refer to the informal sense of recursive grammars above, consistent with RockMagnetist's added references. It is still not much more than a definition, however
Stance: comment
Cited policy: Wikipedia:Be bold (WP:BOLD)