Miniconda script review comments

README, better docs + logging

plugins/python-build/scripts/README.md

@@ -0,0 +1,22 @@
+# Scripts for updating python-build
+
+Install dependencies with `pip install -r requirements.txt`.
+
+## add_miniconda.py
+
+```_add_miniconda
+usage: add_miniconda.py [-h] [-d] [-v]
+
+Script to add non-"latest" miniconda releases. Written for python 3.7. Checks
+the miniconda download archives for new versions, then writes a build script
+for any which do not exist locally, saving it to plugins/python-
+build/share/python-build. Ignores releases below 4.3.30. Also ignores sub-
+patch releases if that major.minor.patch already exists, but otherwise, takes
+the latest sub-patch release for given OS/arch. Assumes all miniconda3
+releases < 4.7 default to python 3.6, and anything else 3.7.
+
+optional arguments:
+  -h, --help     show this help message and exit
+  -d, --dry-run  Do not write scripts, just report them to stdout
+  -v, --verbose  Increase verbosity of logging
+```