Fix: typo where "a url" is written as "an url"

[Kareem-Medhat]

I did a quick search to to be certain and immediately found these websites that also state that it is indeed written and pronounced as "a url":

• https://www.techtarget.com/whatis/feature/Which-is-correct-a-URL-or-an-URL
• https://www.quora.com/Which-is-correct-A-URL-or-An-URL

Description

Changes all occurrences of "an url" to "a url" in changed files

Checklist

• [x] the pull request title describes what this PR does (not a vague title like Update index.md)
• [x] the pull request targets the default branch of the repository (develop)
• [x] the code follows the established code style of the repository
  • npm run prettier:check passes
  • npm run lint:check passes
• [x] tests are added for the changes I made (if any source code was modified)
• [x] documentation added or updated
• [x] I have run the project locally and verified that there are no errors

Fixes

As this is a typo fix I believe opening an issue isn't required as stated in the CONTRIBUTING.md file

(Some very minor changes like a typo fix may be opened without opening a tracking issue.)