Readme "Known issues"

[TobyChaloner]

I think that the readme could remove the invite to try the release-1.1-dev branch. Should there be a new dev branch for recent changes?

"Known issues Many of the issues in the master branch have been fixed in release-1.1-dev branch. Although not tested to be fully stable, release-1.1-dev is stable enough to try out and report any futher issues before it gets merged into master."