minor: wording change DOCS-1254

Author: Sam Kleinman

source/core/indexes.txt

@@ -563,7 +563,7 @@ construction:
   .. versionchanged:: 2.4
      Before 2.4, a :program:`mongod` instance could only build one
      background index per database at a time.
-     
+
   .. versionchanged:: 2.2
      Before 2.2, a single :program:`mongod` instance could only build
      one index at a time.
@@ -796,8 +796,8 @@ the supported languages.
 ``text`` indexes have the following storage requirements and
 performance costs:
 
-- Text indexes change the space allocation method for the documents in
-  the collection to :collflag:`usePowerOf2Sizes`.
+- Text indexes change the space allocation method for all future
+  record allocations in a collection to :collflag:`usePowerOf2Sizes`.
 
 - Text indexes can be large. They contain one index entry for each
   unique post-stemmed word in each indexed field for each document