Prepare release of v2.0

[lipkau]

As the v2.0 milestone is nearly finished, some tasks are still open in order to release v2.0:

• [x] Update documentation
• [x] Update README
• [x] Version bump
• [x] Merge develop into master
• [x] Create release notes
• [x] Add release notes to psd1

[lipkau]

@brianbunke in case it helps, I created my task list of what I have to do before releasing a new version: https://github.com/AtlassianPS/JiraPS/issues/126