clarify the main purpose of the github installation method

[msouff]

No description provided.

[rileyhales]

I think this is good. The only other thing you could talk about is why git install is less preferable than conda. Git is more time consuming, less efficient in various ways, more opportunity for bugs, etc. But thats all optional in my opinion. You can merge this.

[rfun]

@msouff : Could you resolve the conflicts so we can merge this in?

[msouff]

@rfun, I'm not sure why this shows as a conflict. The conflicting file I see is the github_install.rst, which is the file I'm updating. Also, for some reason I am not authorized to merge PRs for this repo.

[rfun]

@msouff : I have increased your level of access to the repo. Let me know if that helps and lets you merge.
Secondly, for the PR, I feel like you don't have the latest Master within the branch you are creating and maybe that's why you are getting this conflict.

Can you try the following commands:

git checkout master
git pull master
git checkout githubinstallcarification
git rebase master
#At this point you should start seeing a merge conflict locally
#complete the rebase and commit your changes after resolving the conflicts
git push -f