Updating the README.md to current times

[lucamilanesio]

The history of this fork was very detailed but misaligned with the current status.
I am grateful you started contributing to the mainline plugin repository and you have +2 permissions on it, should you want to continue to work with the community.

I am working to update GitBlit plugin for Gerrit 2.13 and resolve the Lucene compatibility problems: you are more than welcome to join the effort and get that done.

[tomaswolf]

I don't think I'll merge this.

• The motivation section is correct, it clearly states that this was the state back when I started with this.
• The official plugin's readme file still says one has to clone and build gitblit with special options. For me, that's a "custom-built GitBlit version". (I don't know how up-to-date that readme is, though; it still mentions maven but you recently removed the pom.xml.)
• Since my motivation was questioned initially, I will leave the statements in.
• The final paragraph is also accurate as far as I know. I see no commits to these older branches that would have fixed these errors. Since there are many Gerrit installations in the wild that use pre-2.11 Gerrit, I consider that information useful.

[lucamilanesio]

@tomaswolf true, I need to update the README.md as now the build is done with BUCK and is fully automated 😄
You are free of course to keep your project on GitHub and not to contribute back to the community. I will manually get the useful contributions on this repo and will feedback to the main project, though if we would have use a single repo would have made the operation much easier.

Thank you anyway for your work, it has been and it is useful.

Luca.