Add an installation script and directions

Author: agjohnson

README.md

@@ -1,3 +1,14 @@
-# readthedocs-common
+Read the Docs common development files
+======================================
 
-Shared bits around multiple repositories
+Common shared bits for development and release tooling across multiple
+repositories.
+
+Installing
+----------
+
+To install::
+
+    git submodule add [email protected]:rtfd/common.git common
+    git submodule update
+    make -f common/common.mk

common.mk

@@ -0,0 +1,43 @@
+#      ___          ___          ___          ___          ___          ___
+#     /\  \        /\  \        /\__\        /\__\        /\  \        /\__\
+#    /::\  \      /::\  \      /::|  |      /::|  |      /::\  \      /::|  |
+#   /:/\:\  \    /:/\:\  \    /:|:|  |     /:|:|  |     /:/\:\  \    /:|:|  |
+#  /:/  \:\  \  /:/  \:\  \  /:/|:|__|__  /:/|:|__|__  /:/  \:\  \  /:/|:|  |__
+# /:/__/ \:\__\/:/__/ \:\__\/:/ |::::\__\/:/ |::::\__\/:/__/ \:\__\/:/ |:| /\__\
+# \:\  \  \/__/\:\  \ /:/  /\/__/~~/:/  /\/__/~~/:/  /\:\  \ /:/  /\/__|:|/:/  /
+#  \:\  \       \:\  /:/  /       /:/  /       /:/  /  \:\  /:/  /     |:/:/  /
+#   \:\  \       \:\/:/  /       /:/  /       /:/  /    \:\/:/  /      |::/  /
+#    \:\__\       \::/  /       /:/  /       /:/  /      \::/  /       /:/  /
+#     \/__/        \/__/        \/__/        \/__/        \/__/        \/__/
+#
+
+# Default
+default: link pre-commit
+
+# Config rules
+CONFIG = \
+	prospector.yml
+
+CONFIG_HIDDEN = \
+	.eslintrc \
+	.flake8 \
+	.isort.cfg \
+	.pep8 \
+	.pre-commit-config.yaml \
+	.style.yapf \
+
+CONFIG_ALL = $(CONFIG) $(CONFIG_HIDDEN)
+
+
+.PHONY: link default pre-commit ignore
+
+link: $(CONFIG_ALL)
+
+$(CONFIG): %: common/%
+	[ -e "$@" ] || (ln -s $? $@ && git add $@)
+
+$(CONFIG_HIDDEN): .%: common/%
+	[ -e "$@" ] || (ln -s $? $@ && git add $@)
+
+pre-commit:
+	pre-commit clean