community/py3-smmap2: add comment about mistagged version

see pypi project page for smmap

community/py3-smmap2/APKBUILD

@@ -3,6 +3,7 @@
 pkgname=py3-smmap2
 pkgver=5.0.1
 pkgrel=0
+# 6.0.0 was yanked and replaced with 5.0.1, should not be upgraded to
 pkgdesc="pure Python3 implementation of a sliding window memory map manager"
 url="https://github.com/gitpython-developers/smmap"
 arch="noarch"