add pypi

doc/install.mdwn

@@ -23,6 +23,7 @@ detailed instructions             | quick install
 [[OpenBSD]]                       | `pkg_add git-annex`
 [[Android]]                       | **beta**
 [[Windows]]                       | **beta**
+[PyPi][pypi]                      | `uv tool install git-annex`
 """]]
 
 ## Historical builds
@@ -39,3 +40,5 @@ it [[from source|fromsource]].
 
  * [[autobuild overview|builds]]
  * [[upgrades]]
+
+[pypi]: https://pypi.org/project/git-annex/