issue1582: improve description of splicemap syntax in help.

hgext/convert/__init__.py

@@ -79,7 +79,7 b' def convert(ui, src, dest=None, revmapfi'
     useful if you want to e.g. give a Subversion merge two parents, or
     graft two disconnected series of history together.  Each entry
     contains a key, followed by a space, followed by one or two
-    values, separated by spaces.  The key is the revision ID in the
+    comma-separated values.  The key is the revision ID in the
     source revision control system whose parents should be modified
     (same format as a key in .hg/shamap).  The values are the revision
     IDs (in either the source or destination revision control system)

tests/test-convert.out

@@ -64,7 +64,7 b' convert a foreign SCM repository to a Me'
     useful if you want to e.g. give a Subversion merge two parents, or
     graft two disconnected series of history together.  Each entry
     contains a key, followed by a space, followed by one or two
-    values, separated by spaces.  The key is the revision ID in the
+    comma-separated values.  The key is the revision ID in the
     source revision control system whose parents should be modified
     (same format as a key in .hg/shamap).  The values are the revision
     IDs (in either the source or destination revision control system)