largefiles: fix misleading comments in lfutil instore and storepath

Problem in both cases is cache in largefiles has assigned
meaning - user cache which is additional place to get/put
files. Those two function works on store - the main place
to store largefiles in the repository - .hg/largefiles and
using "cache" to describe it is misleading.

hgext/largefiles/lfutil.py

@@ -190,12 +190,11 def listlfiles(repo, rev=None, matcher=N
             if rev is not None or repo.dirstate[f] != '?']
 
 def instore(repo, hash, forcelocal=False):
-    '''Return true if a largefile with the given hash exists in the user
-    cache.'''
+    '''Return true if a largefile with the given hash exists in the store'''
     return os.path.exists(storepath(repo, hash, forcelocal))
 
 def storepath(repo, hash, forcelocal=False):
-    '''Return the correct location in the repository largefiles cache for a
+    '''Return the correct location in the repository largefiles store for a
     file with the given hash.'''
     if not forcelocal and repo.shared():
         return repo.vfs.reljoin(repo.sharedpath, longname, hash)