Rephrase docstrings

Change the "synonym set" naming to simply "synonym"

algoliasearch/index.py

@@ -589,7 +589,7 @@ def get_synonym(self, object_id):
 
     def delete_synonym(self, object_id, forward_to_slaves=False):
         """
-        Delete a synonym set from the index.
+        Delete a synonym from the index.
 
         @param object_id the unique identifier of the synonyms set to delete
         @param forward_to_slaves (optional) should the changes be forwarded to
@@ -602,7 +602,7 @@ def delete_synonym(self, object_id, forward_to_slaves=False):
 
     def clear_synonyms(self, forward_to_slaves=False):
         """
-        Delete all synonym sets from the index.
+        Delete all synonyms from the index.
 
         @param forward_to_slaves (optional) should the changes be forwarded to
             slave indexes
@@ -614,7 +614,7 @@ def clear_synonyms(self, forward_to_slaves=False):
 
     def search_synonyms(self, query, types=[], page=None, hits_per_page=100):
         """
-        Search for synonym sets from this index.
+        Search for synonyms from this index.
 
         @param query the full text query
         @param types (optional) the types of the synonyms to search for.