This commit maps the "Publish" action inside CodiMD/HedgeDoc to the
share URL feature.

This commit improves a bit the ShareURL internal API by wrapping the
returned URL into a proper `ShareURL` type (that internally uses a typed
representation for the URL).

Fixes #374 by not using a bespoke config file, but rather setting
the `window.domain` and `window.urlpath` via regex substitution.

This avoids using an old `window.version` that would cause the
refresh modal to popup every time after each upgrade of HedgeDoc /
CodiMD.

The new files in `docs/` explain:
1. How to get one's editor to play nice with HLS
   and the Gargantext project
2. To interact with the server/database from within GHCI

A reference to them has been added to the `README`.

This time I think I am clear on what the building & running process is
and what the purpose of each command is, and I tried to make it clear again.

This may be deemed too verbose:
- Maybe I went into too many basic details, I'll be happy to discuss
  what the right level of detail is;
- But I also think there are too many ways to do the same thing
  documented in the README. It might be worth settling on one recommended way,
  and documenting the rest in an appendix or something like that.

Fixed some typos introduced in the previous edit,
clarified a couple of points, and restructured the doc some more
as I got a better grasp on the process.

While doing this, I have also fixed a bug in the current implementation
of ThrowAll (formerly named `throwAll'`).

It integrates servant-routes which allows to list and export the
server backend routes.

Various clarifications and reformulations based on my experience using
the README to build and run Gargantext. In particular:
- Information related to development has been given its own section
- Docker Compose has been added to the list of prerequisites
- Information pertaining to using Stack has been moved to an annex file
- The content to be copypasted into a `cabal.project.local` file has been moved
  out of the README into a separate file `cabal.project.local_toCopy`

Those may not be the best decisions, I am happy to discuss them if
needed