Add Obsolete State to OEPs

Hey All, I want to make a change to OEP-1 to introduce a new state(“Obsolete”) . I’m hoping to use this to further clean up the OEPs space and clearly mark which OEPs are no longer relevant. If you have thoughts/feedback, drop it on the PR. Currently the only way that an OEP can go away is if it is replaced, which seemed not quite correct to me. eg. The OEP for upgrading to Python 3, we aren’t replacing it but it’s also not something anyone needs to care about anymore.

PR: doc: Update OEP-1 by feanil · Pull Request #246 · edx/open-edx-proposals · GitHub