Minor grammar fixed in database-references.txt

Using logical quotes.

Author: dandv

source/applications/database-references.txt

@@ -10,7 +10,7 @@ Database References
 .. default-domain:: mongodb
 
 MongoDB does not support joins. In MongoDB some data is
-"denormalized," or stored with related data in :term:`documents
+"denormalized", or stored with related data in :term:`documents
 <document>` to remove the need for joins. However, in some cases it
 makes sense to store related information in separate documents,
 typically in different collections or databases.
@@ -39,7 +39,7 @@ MongoDB applications use one of two methods for relating documents:
    links between documents if your database must interact with
    multiple frameworks and tools.
 
-Unless you have a compelling reason for using a DBRef use manual
+Unless you have a compelling reason for using a DBRef, use manual
 references.
 
 .. [#official-driver] Some community supported drivers may have
@@ -108,7 +108,7 @@ Background
 ~~~~~~~~~~
 
 DBRefs are a convention for representing a :term:`document`, rather
-than a specific reference "type." They include the name of the
+than a specific reference "type". They include the name of the
 collection, and in some cases the database, in addition to the
 value from the ``_id`` field.
 
@@ -144,7 +144,7 @@ Thus a DBRef document would resemble the following:
 
 .. note::
 
-   The order of fields in the DBRef matter, and you must use the above
+   The order of fields in the DBRef matters, and you must use the above
    sequence when using a DBRef.
 
 Support