cheat sheet: tweak the transplanted commit annotations

Remove the "prime" from the stacked D and E because
I think it's confusing.

The idea of the D' annotation is that D is somehow a shorthand for a
commit ID, and D' is meant to suggest that the transplanted commit has a
different commit ID.

But with the stacked D and E, the two D and E being grouped together are
already doing the work to show that the new commit is modified in some
way, so we don't need to add the "prime" (and it's not clear to me what
the prime would mean)

Author: jvns

content/cheat-sheet/_index.html

@@ -510,7 +510,7 @@ <h3>Combine with squash merge:</h3>
             C [label="C", pos="2,1!"];
             D [label="D", color="#f14e32", pos="2,0!"];
             E [label="E", color="#f14e32", pos="3,0!"];
-            S [label="D&#x2032;\nE&#x2032;", color="#f14e32", pos="3,1!", width=0.6, height=0.8];
+            S [label="D\nE", color="#f14e32", pos="3,1!", width=0.6, height=0.9];
 
             main_label [label="main", shape=plaintext, pos="5,1!", fixedsize=false];
             main_label -> S [dir=forward];