Fix documentation typos

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/installation/linux/centos.md

@@ -32,7 +32,7 @@ display your kernel version:
     $ uname -r
     3.10.0-229.el7.x86_64
 
-Finally, is it recommended that you fully update your system. Please keep in
+Finally, it is recommended that you fully update your system. Please keep in
 mind that your system should be fully patched to fix any potential kernel bugs.
 Any reported kernel bugs may have already been fixed on the latest kernel
 packages.

docs/userguide/networking/default_network/configure-dns.md

@@ -61,7 +61,7 @@ Four different options affect container domain name services.
       Using this option as you <code>run</code> a container gives the new
       container's <code>/etc/hosts</code> an extra entry named
       <code>ALIAS</code> that points to the IP address of the container
-      identified by <code>CONTAINER_NAME_or_ID<c/ode>. This lets processes
+      identified by <code>CONTAINER_NAME_or_ID</code>. This lets processes
       inside the new container connect to the hostname <code>ALIAS</code>
       without having to know its IP.  The <code>--link=</code> option is
       discussed in more detail below. Because Docker may assign a different IP