[PATCHES] pglister: Add README.md and INSTALL.md

Hello,

As I'm done with the ansible script [1] to install pglister and all related components, I've attempted writing a documentation to describe the whole install procedure.
I've done my best to document all steps and not forget any of them. I've not mentioned the data.sql issue because I've considered this will be merged into a Django migration (hopefully I can do that soon).
As mentioned, I've used pgweb for auth, but that's not really convenient because it's not KISS. I'm going to start another thread about that.
I'm also adding a basic README to give some general information and point to the install document.

[1]: https://gitlab.com/cmatte/ansible-pglister
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Célestin Matte