Linux getting started page is out of date

[githubUser435543]

https://pros.cs.purdue.edu/v5/getting-started/linux.html is out-of-date and very frustrating to follow. Here are the things that need to be updated:

1. The link to the arm developer site is now https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
   Make sure to update the instructions with it, some things like the file compression formats are different. While you're at it change the 7.2 to 14.3.

2. Installing the CLi requires a virtual environment and the command is pip -m install pros-cli "click==8" because click broke the package.

3. Atom is dead now so might want to remove that part