histedit: correct spelling etc in more comments

Spotted during review of another patch.

hgext/histedit.py

@@ -1034,8 +1034,8 b' def processreplacement(state):'
     allsuccs = set()
     replaced = set()
     fullmapping = {}
-    # initialise basic set
-    # fullmapping record all operations recorded in replacement
+    # initialize basic set
+    # fullmapping records all operations recorded in replacement
     for rep in replacements:
         allsuccs.update(rep[1])
         replaced.add(rep[0])