Minor typos.

source/core/indexes.txt

@@ -106,7 +106,7 @@ The ``_id`` field is the :term:`primary key` for the collection, and
 every document *must* have a unique ``_id`` field. You may store any
 unique value in the ``_id`` field. The default value of ``_id`` is an
 :term:`ObjectID` on every :method:`~db.collection.insert()`
-operation. An :term:`ObjectId` is a 12-byte unique identifiers
+operation. An :term:`ObjectId` is a 12-byte unique identifier
 suitable for use as the value of an ``_id`` field.
 
 .. note::

source/tutorial/configure-linux-iptables-firewall.txt

@@ -13,7 +13,7 @@ system.
 
 This document outlines basic firewall configurations for ``iptables``
 firewalls on Linux. Use these approaches as a starting point for your
-larger networking organization. For a detailed over view of security
+larger networking organization. For a detailed overview of security
 practices and risk management for MongoDB, see :doc:`/core/security`.
 
 .. seealso:: For MongoDB deployments on Amazon's web services, see the
@@ -26,7 +26,7 @@ Overview
 Rules in ``iptables`` configurations fall into chains, which describe
 the process for filtering and processing specific streams of
 traffic. Chains have an order, and packets must pass through earlier
-rules in a chain to reach later rules. This document only the
+rules in a chain to reach later rules. This document addresses only the
 following two chains:
 
 ``INPUT``