[pkg-config] Update website URL
[autotools] Add README as symlink to README.md to make "make dist" happy
[Buildsystem] Make sure to distribute all the shiny new documentation
[Release] Bump version info to 2.3.0-rc2
Merge branch 'releases/2.3'

Pull in build system fixes from release branch.

* releases/2.3:
  [Release] Bump version info to 2.3.0-rc2
  [Buildsystem] Make sure to distribute all the shiny new documentation
  [autotools] Add README as symlink to README.md to make "make dist" happy
  [pkg-config] Update website URL

Conflicts:
	README.md
	dune.module