docs(test): Document how to install the VCS hooks

Move the VCS hook installation to a dedicated target to emphasize that it's opt-in.
Document why one might use the hooks and document how to install them.

Makefile

@@ -29,20 +29,20 @@ APPNAME=tahoe-lafs
 default:
 	@echo "no default target"
 
-.PHONY: build
-## Set up and build for local development
-build: .tox/log/create-venvs.log .git/hooks/pre-commit .git/hooks/pre-push
+.PHONY: install-vcs-hooks
+## Install the VCS hooks to run linters on commit and all tests on push
+install-vcs-hooks: .git/hooks/pre-commit .git/hooks/pre-push
 
 .PHONY: test
 ## Run all tests and code reports
-test: build
+test: .tox/log/create-venvs.log
 # Run codechecks first since it takes the least time to report issues early.
 	tox --develop -e codechecks
 # Run all the test environments in parallel to reduce run-time
 	tox --develop -p auto -e 'py27,py36,pypy27'
 .PHONY: test-py3-all
 ## Run all tests under Python 3
-test-py3-all: build
+test-py3-all: .tox/log/create-venvs.log
 	tox --develop -e py36 allmydata
 
 # This is necessary only if you want to automatically produce a new

docs/INSTALL.rst

@@ -286,7 +286,16 @@ result in a "all tests passed" mesage::
  PASSED (skips=7, expectedFailures=3, successes=1176)
  __________________________ summary ___________________________________
    py27: commands succeeded
-   congratulations :) 
+   congratulations :)
+
+You may also install VCS/git hooks to run linters and code checks to catch
+common errors before each commit and to run the full self-test suite to find
+less obvious regressions before each push to a remote.  Not that running the
+full self-test suite takes several minutes to expecting pushing to take some
+time.  If you can't or don't want to wait for the hooks in some cases, use
+the ``--no-verify`` option to ``git commit ...`` or ``$ git push ...``::
+
+  $ make install-vcs-hooks
 
 Common Problems
 ===============