Add image captions in Replace section

Author: petk

book/07-git-tools/sections/replace.asc

@@ -29,7 +29,8 @@ We want to break this up into two lines of history.
 One line goes from commit one to commit four - that will be the historical one.
 The second line will just be commits four and five - that will be the recent history.
 
-image::images/replace1.png[]
+.Example Git history
+image::images/replace1.png[Example Git history]
 
 Well, creating the historical history is easy, we can just put a branch in the history and then push that branch to the `master` branch of a new remote repository.
 
@@ -44,7 +45,8 @@ c6e1e95 (history) Fourth commit
 c1822cf First commit
 ----
 
-image::images/replace2.png[]
+.Creating a new `history` branch
+image::images/replace2.png[Creating a new `history` branch]
 
 Now we can push the new `history` branch to the `master` branch of our new repository:
 
@@ -97,7 +99,8 @@ On occasions when we're doing weirder things like this, they allow us to do real
 You can read more about plumbing commands in <<ch10-git-internals#_plumbing_porcelain>>.
 =====
 
-image::images/replace3.png[]
+.Creating a base commit using `commit-tree`
+image::images/replace3.png[Creating a base commit using `commit-tree`]
 
 OK, so now that we have a base commit, we can rebase the rest of our history on top of that with `git rebase --onto`.
 The `--onto` argument will be the SHA-1 we just got back from `commit-tree` and the rebase point will be the third commit (the parent of the first commit we want to keep, `9c68fdc`):
@@ -110,7 +113,8 @@ Applying: fourth commit
 Applying: fifth commit
 ----
 
-image::images/replace4.png[]
+.Rebasing the history on top of the base commit
+image::images/replace4.png[Rebasing the history on top of the base commit]
 
 OK, so now we've re-written our recent history on top of a throw away base commit that now has instructions in it on how to reconstitute the entire history if we wanted to.
 We can push that new history to a new project and now when people clone that repository, they will only see the most recent two commits and then a base commit with instructions.
@@ -172,7 +176,8 @@ c1822cf First commit
 
 Cool, right?  Without having to change all the SHA-1s upstream, we were able to replace one commit in our history with an entirely different commit and all the normal tools (`bisect`, `blame`, etc) will work how we would expect them to.
 
-image::images/replace5.png[]
+.Combining the commits with `git replace`
+image::images/replace5.png[Combining the commits with `git replace`]
 
 Interestingly, it still shows `81a708d` as the SHA-1, even though it's actually using the `c6e1e95` commit data that we replaced it with.
 Even if you run a command like `cat-file`, it will show you the replaced data: