DOCSP 23684 making sparse index example more consistent (#1442)

* DOCSP-23684 making index example more consistent

* DOCSP-23684 making sparse index example consistent

* DOCSP-23684 making sparse index example consistent

Author: ltran-mdb

source/core/index-sparse.txt

@@ -234,10 +234,9 @@ index permits the following :doc:`insert operations
 .. code-block:: javascript
 
    db.scores.insertMany( [
-      { "userid": "AAAAAAA", "score": 43 },
-      { "userid": "BBBBBBB", "score": 34 },
-      { "userid": "CCCCCCC" },
-      { "userid": "DDDDDDD" }
+      { "userid": "newbie", "score": 43 },
+      { "userid": "abby", "score": 34 },
+      { "userid": "nina" }
    ] )
 
 However, the index *would not permit* the addition of the following
@@ -247,8 +246,8 @@ and ``90``:
 .. code-block:: javascript
 
    db.scores.insertMany( [
-      { "userid": "AAAAAAA", "score": 82 },
-      { "userid": "BBBBBBB", "score": 90 }
+      { "userid": "newbie", "score": 82 },
+      { "userid": "abby", "score": 90 }
    ] )
 
 .. _sparse-and-non-sparse_example: