General wiki cleanup.
Remove hand-installed Jenkins instructions, point to proper plugin.
Point to xeqi's version ranges article.
Use `lein deps :tree` to check frozen snapshot timestamps.
mention pre-commit hooks.
Mention repositories from user-level profiles.
Improve punctuation
use-fixtures example.
Cover CI, testing, and a snapshots locking example.
Expand repeatability entry.
Add the start of a Repeatability page.