DOC: Add CoC to the README

[sparalic]

@datapythonista : Add CoC to README file

[TomAugspurger]

Sorry about the CI failures again @sparalic. If you merge master and push, things should be fixed

$ git fetch upstream
$ git merge upstream/matser
$ # git add and commit stuff
$ git push origin pandas-coc

You can also put in @gfyoung's request change at the same time if you want

[sparalic]

@TomAugspurger and @gfyoung thank you for all of your help. @TomAugspurger, I tried merging with the master and pushing as you suggested, but some of the CI test failed again.

[gfyoung]

@sparalic : I restarted the failing build for you to see if the failure goes away. If not, you should merge with master and push.

[sparalic]

@datapythonista and @gfyoung thank you!

[datapythonista]

lgtm, thanks @sparalic

[TomAugspurger]

You are just not having luck with our CI @sparalic 😄 The windows failure is unrelated. Tracking it in #27902.

This is good to merge once the doc build passes.

[TomAugspurger]

Thanks @sparalic!