Fixed typos in README.md file

[VardaanAggarwal]

Fixes Issue

Browser extension of GitPod for Chrome and Firefox were not clearly mentioned, and was unable to read.

Check List (Check all the applicable boxes)

• [👍🏼] My code follows the code style of this project.
• [👍🏼] My change requires changes to the documentation.
• [👍🏼] I have updated the documentation accordingly.
• [👍🏼] All new and existing tests passed.
• [👍🏼] This PR does not contain plagiarized content.
• [👍🏼] The title of my pull request is a short description of the requested changes.

[VardaanAggarwal]

What merging this PR will do ? Before :

After :