Fixed plural version of URLs where it was referred to as "URL's"

A simple fix to a couple of typos in the documentation. It's my first time sending a pull request to a github repo so I hope I've done it right. If all ok there are lots more typos/grammar bits I can update.

| Q             | A
| ------------- | ---
| Doc fix?      | yes ? (Fixes typos, not sure if this is the meaning of "Doc fix")
| New docs?     | no
| Applies to    | all
| Fixed tickets | none