mq: fix qapplied --last and qprev documentation (issue3282)

qapplied --last is qprev not qtop.

v2:
- Replace "previous" with "preceding" as suggested here and there

hgext/mq.py

@@ -1929,7 +1929,7 b' def delete(ui, repo, *patches, **opts):'
     return 0
 
 @command("qapplied",
-         [('1', 'last', None, _('show only the last patch'))
+         [('1', 'last', None, _('show only the preceding applied patch'))
           ] + seriesopts,
          _('hg qapplied [-1] [-s] [PATCH]'))
 def applied(ui, repo, patch=None, **opts):
@@ -2224,7 +2224,7 b' def next(ui, repo, **opts):'
 
 @command("qprev", seriesopts, _('hg qprev [-s]'))
 def prev(ui, repo, **opts):
-    """print the name of the previous applied patch
+    """print the name of the preceding applied patch
 
     Returns 0 on success."""
     q = repo.mq

tests/test-mq.t

@@ -74,7 +74,7 b' help'
    qnew          create a new patch
    qnext         print the name of the next pushable patch
    qpop          pop the current patch off the stack
-   qprev         print the name of the previous applied patch
+   qprev         print the name of the preceding applied patch
    qpush         push the next patch onto the stack
    qqueue        manage multiple patch queues
    qrefresh      update the current patch