docs(quickstart): Note on general availability

Author: tony

docs/quickstart.md

@@ -24,8 +24,14 @@ If you are a Homebrew user you can install it with:
 $ brew install tmuxp
 ```
 
+(developmental-releases)=
+
 ### Developmental releases
 
+New versions of tmuxp are published to PyPI as alpha, beta, or release candidates.
+In their versions you will see notfication like `a1`, `b1`, and `rc1`, respectively.
+`1.10.0b4` would mean the 4th beta release of `1.10.0` before general availability.
+
 - [pip](https://pip.pypa.io/en/stable/):
 
   ```console