Updating readme

Author: iriark01

readme.md

@@ -1,11 +1,11 @@
 # Mbed OS 5 documentation
 
-This is the documentation source for Mbed OS 5.
+This is the documentation source for Mbed OS 5. It's optimised to be read on [the documentation site](https://os.mbed.com/docs/latest/).
 
-If you want to contribute, please read our [contribution guide](https://os.mbed.com/contributing/).
+If you want to contribute, please read our [contribution guide](https://os.mbed.com/docs/latest/contributing/index.html).
 
 Please open pull requests against either:
 
-* `new_engine` - this is our development branch.
-* `5.8` - this is the latest live version.
-* Older version branches probably don't require fixes; please open an issue if you think we're wrong.
+- `development` - this is our development branch.
+- `5.11` - this is the latest live version.
+- Older version branches probably don't require fixes; please open an issue if you think we're wrong.