Update Readme

[thimmy687]

This PR updates the Readme.
The generic template information are removed and the some gerrit plugin information are added

[RussKie]

LGTM.
I'd like to have an a better understanding of GitExtensionsReferenceSource property.

[mast-eu]

I'd like to have an a better understanding of GitExtensionsReferenceSource property.

In general, the master branch of any plugin should be build against the latest GE nightly build (i.e. to incorporate API changes that are not yet included in a GE release). Thus, we get the GitExtensionsReferenceSource from the CI (=AppVeyor).

On the other hand, all release branches must (generally) be build against the latest stable GE release, otherwise they might fail in an end users' installation. In this case the GitExtensionsReferenceSource is GitHub, where the released artifacts are stored.

More complex scenarios might require to build with an older GE release / CI build. That's when you'll need to change also GitExtensionsReferenceVersion:

GitExtensions.GerritPlugin/src/GitExtensions.GerritPlugin/GitExtensions.GerritPlugin.csproj.user

Lines 6 to 9 in c25d49c

	<!-- 'latest' or 'v3.1' (= tag from GitHub releases) or 'v3.1.0.5877' (= build number from AppVeyor)-->
	<GitExtensionsReferenceVersion>latest</GitExtensionsReferenceVersion>
	<!-- 'GitHub' or 'AppVeyor' -->
	<GitExtensionsReferenceSource>AppVeyor</GitExtensionsReferenceSource>

@thimmy687 : Please base your work on https://github.com/gitextensions/GitExtensions.GerritPlugin/tree/master, not on https://github.com/gitextensions/GitExtensions.GerritPlugin/tree/release/1.0.
It's ok if you want to include b692b86 and a6b4645 in your PR. Both commits should, in effect, be on master, too. But for the reason explained above, 6e5c874 should definitely not be on the master branch.

[thimmy687]

I guess we need first fix this #17, before the build will be able to build.

[RussKie]

The subject of the PR and the content of the PR do not match...
Please separate and make targeted changes.