fix issue bma noticed (why does it use "r2"?)

doc/bugs/Mercurial_example_diffurl_should_read_r2__44___not_changeset.mdwn

@@ -6,4 +6,6 @@ should be:
 
     diffurl => "http://localhost:8000/?fd=\[[r2]];file=\[[file]]",
 
-(changeset doesn't get expanded; r2 does, to what appears to be The Right Thing)
+(changeset doesn't get expanded; r2 does, to what appears to be The Right Thing)
+
+[[done]]

doc/ikiwiki.setup

@@ -41,7 +41,7 @@ use IkiWiki::Setup::Standard {
 	# Mercurial stuff.
 	#rcs => "mercurial",
 	#historyurl => "http://localhost:8000/", # hg serve'd local repository
-	#diffurl => "http://localhost:8000/?fd=[[changeset]];file=[[file]]",
+	#diffurl => "http://localhost:8000/?fd=[[r2]];file=[[file]]",
 
 	# Monotone stuff
 	#rcs => "monotone",