minor spelling/grammar edits

Author: kay-kim

source/tutorial/isolate-sequence-of-operations.txt

@@ -39,13 +39,13 @@ manage isolated sequences of operations:
 Update if Current
 -----------------
 
-In this patter, you will: 
+In this pattern, you will: 
 
-- queries for a document, 
+- query for a document, 
 
-- modifies the fields in that document
+- modify the fields in that document
 
-- and updates the fields of a document *only if* the fields have not
+- and update the fields of a document *only if* the fields have not
   changed in the collection since the query.
 
 Consider the following example in JavaScript which attempts to update