Fixing typos in listeners.md
Fixing typos in listeners.md

- ParserRuleContext does not have type parameters
- Confusing sentence cleaned up a little
chandler14362/antlr4,ericvergnaud/antlr4,Pursuit92/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,chandler14362/antlr4,parrt/antlr4,chandler14362/antlr4,parrt/antlr4,wjkohnen/antlr4,antlr/antlr4,Pursuit92/antlr4,ericvergnaud/antlr4,chandler14362/antlr4,parrt/antlr4,Distrotech/antlr4,wjkohnen/antlr4,antlr/antlr4,parrt/antlr4,antlr/antlr4,ericvergnaud/antlr4,antlr/antlr4,ericvergnaud/antlr4,ericvergnaud/antlr4,Pursuit92/antlr4,Distrotech/antlr4,antlr/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,chandler14362/antlr4,Pursuit92/antlr4,parrt/antlr4,chandler14362/antlr4,antlr/antlr4,parrt/antlr4,wjkohnen/antlr4,antlr/antlr4,Pursuit92/antlr4,parrt/antlr4,chandler14362/antlr4,antlr/antlr4,chandler14362/antlr4,Distrotech/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,Pursuit92/antlr4,parrt/antlr4,wjkohnen/antlr4,antlr/antlr4,chandler14362/antlr4,Pursuit92/antlr4,Pursuit92/antlr4,Pursuit92/antlr4,Distrotech/antlr4,Distrotech/antlr4,antlr/antlr4,wjkohnen/antlr4,parrt/antlr4,parrt/antlr4,wjkohnen/antlr4,ericvergnaud/antlr4,ericvergnaud/antlr4