docs(scope): clean up grammar and improve clarity
docs(scope): clean up grammar and improve clarity

Some typos fixed and grammar improved:
- withing -> within
- life-cycle -> life cycle
- extraneous spaces
- grammar mistakes
- missing commas
- reworded unclear statements

Closes #3920

ammula88/angular.js,ammula88/angular.js,ammula88/angular.js,ammula88/angular.js,ammula88/angular.js