Fix formatting issue

Asciidoctor documentation suggests solution to properly render
a possessive monospaced phrase by using unconstrained formatting.
However, this approach does not work when one more monospaced phrase
follows in the same paragraph.
The simplest workaround was suggested by the Asciidoctor project lead:
Dan Allen.

Author: yugaego

book/07-git-tools/sections/advanced-merging.asc

@@ -580,7 +580,7 @@ The history with the revert commit looks like this:
 .History after `git revert -m 1`
 image::images/undomerge-revert.png[History after `git revert -m 1`]
 
-The new commit `^M` has exactly the same contents as `C6`, so starting from here it's as if the merge never happened, except that the now-unmerged commits are still in `HEAD`'s history.
+The new commit `^M` has exactly the same contents as `C6`, so starting from here it's as if the merge never happened, except that the now-unmerged commits are still in `HEAD`’s history.
 Git will get confused if you try to merge `topic` into `master` again:
 
 [source,console]