update README with new release info

README.md

@@ -11,16 +11,26 @@ providing a consistent API regardless of how the configuration was created.
 
 ## Releases
 
-### Stable (2.2)
-OmegaConf 2.2 is the current stable version.
-* [What's new](https://github.com/omry/omegaconf/releases/tag/v2.2.1)
-* [Documentation](https://omegaconf.readthedocs.io/en/2.2_branch/)
-* [Source code](https://github.com/omry/omegaconf/tree/2.2_branch)
+### Stable (2.3)
+OmegaConf 2.3 is the current stable version.
+* [What's new](https://github.com/omry/omegaconf/releases/tag/v2.3.0)
+* [Documentation](https://omegaconf.readthedocs.io/en/2.3_branch/)
+* [Source code](https://github.com/omry/omegaconf/tree/2.3_branch)
 
 Install with `pip install --upgrade omegaconf`
 
+### Previous release (2.2)
+
+* [What's new](https://github.com/omry/omegaconf/releases/tag/v2.1.1)
+* [Documentation](https://omegaconf.readthedocs.io/en/2.1_branch/)
+* [Slides](https://docs.google.com/presentation/d/e/2PACX-1vT_UIV7hCnquIbLUm4NnkUpXvPEh33IKiUEvPRF850WKA8opOlZOszjKdZ3tPmf8u7hGNP6HpqS-NT5/pub?start=false&loop=false&delayms=3000)
+* [Source code](https://github.com/omry/omegaconf/tree/2.1_branch)
+
+Install with `pip install omegaconf==2.1`
+
+
 ### Previous release (2.1)
-OmegaConf 2.1 is the current stable version.
+
 * [What's new](https://github.com/omry/omegaconf/releases/tag/v2.1.1)
 * [Documentation](https://omegaconf.readthedocs.io/en/2.1_branch/)
 * [Slides](https://docs.google.com/presentation/d/e/2PACX-1vT_UIV7hCnquIbLUm4NnkUpXvPEh33IKiUEvPRF850WKA8opOlZOszjKdZ3tPmf8u7hGNP6HpqS-NT5/pub?start=false&loop=false&delayms=3000)