docs(error/badname): Fixed Grammatical Error

In badname.ngdoc, the phrase 'in a context where it is not <b>allow</b>' is changed to 'in a context where is is not <b>allowed</b>'. The grammatical error made this document slightly confusing.

CHANGE:  Occurs when you try to use the name `hasOwnProperty` in a context where it is not allowed.