WIP
Write about useful git commands
Link to Paul's blog
Change to use git diff-tree
Reformulate the intro a bit
Add an evocative image
Reformulate awkward sentence
Better caption
Remove underscores
Remove redundant adverb
Define "PR"
Update reviewing-merge-commits.markdown
Treat SHA as code
Add more details about merging and merge commits
Move definition of merge commit before we use it
Add link to full diff
Clarify the summary
Rephrase awkward sentence
Point out the problem with large conflict changes
Add conclusion