developer tips for updating after merging `SimPEG` --> `simpeg`

[lheagy]

After merging #1430, a lot of folks are going to face merge conflicts, so I am starting this issue as a place where we can help each other navigate through those conflicts. Please feel free to add questions or tips to this issue as you work on bringing in this latest change

directory naming

As a first note, many operating systems don't track the case of directories. When I pulled main, the directory containing all of our code is still called SimPEG. So I needed to manually rename it to simpeg.

cleaning up the pycache files

It is also a good idea to run make clean from the root directory to clear out the old pycache files

[santisoler]

To cleanup a git repo we can use git clean -xdf ..

[!WARNING] It will remove all files in your repo that is not being tracked. Make sure you want to run this command before hitting enter. Consider making a copy of your repo if you are unsure.