Update db.collection.validate.txt

Author: jameswahlin

source/reference/method/db.collection.validate.txt

@@ -41,6 +41,6 @@ Behavior
 :method:`db.collection.validate()` obtains an exclusive lock on the
 collection. This will block all reads and writes on the collection
 until the operation finishes. When run on a secondary, the operation
-can sblock all other operations on that secondary until it finishes.
+can block all other operations on that secondary until it finishes.
 
 .. seealso:: :doc:`/reference/command/validate`