Update usage section example commands

Change <repo> to <local-repo> so that it's clear that we invoke from a local repository;
Add 'git checkout HEAD' command as we need to run it as the final step.

Thanks

README.md

@@ -33,7 +33,8 @@ Using hg-fast-export is quite simple for a mercurial repository <repo>:
 mkdir repo-git # or whatever
 cd repo-git
 git init
-hg-fast-export.sh -r <repo>
+hg-fast-export.sh -r <local-repo>
+git checkout HEAD
 ```
 
 Please note that hg-fast-export does not automatically check out the

hg-fast-export.py

@@ -153,9 +153,13 @@ def sanitize_name(name,what="branch", mapping={}):
   # modifying names which previously were not touched it will break
   # preexisting setups which are doing incremental imports.
   #
-  # Use the -B and -T options to mangle branch and tag names
-  # instead. If you have a source repository where this is too much
-  # work to do manually, write a tool that does it for you.
+  # Fast-export tries to not inflict arbitrary naming policy on the
+  # user, instead it aims to provide mechanisms allowing the user to
+  # apply their own policy. Therefore do not add a transform which can
+  # already be implemented with the -B and -T options to mangle branch
+  # and tag names. If you have a source repository where this is too
+  # much work to do manually, write a tool that does it for you.
+  #
 
   def dot(name):
     if not name: return name