modify some grammar mistakes in /doc/

docs/admin/accessing-the-api.md

@@ -86,7 +86,7 @@ For version 1.2, clusters created by `kube-up.sh` are configured so that no auth
 required for any request.
 
 As of version 1.3, clusters created by `kube-up.sh` are configured so that the ABAC authorization
-modules is enabled.  However, its input file is initially set to allow all users to do all
+modules are enabled.  However, its input file is initially set to allow all users to do all
 operations.  The cluster administrator needs to edit that file, or configure a different authorizer
 to restrict what users can do.
 

docs/admin/apparmor/index.md

@@ -384,7 +384,7 @@ Specifying the default profile to apply to containers when none is provided:
 - **key**: `apparmor.security.beta.kubernetes.io/defaultProfileName`
 - **value**: a profile reference, described above
 
-Specifying the list of profiles Pod containers are allowed to specify:
+Specifying the list of profiles Pod containers is allowed to specify:
 
 - **key**: `apparmor.security.beta.kubernetes.io/allowedProfileNames`
 - **value**: a comma-separated list of profile references (described above)

docs/admin/federation/index.md

@@ -110,7 +110,7 @@ $ KUBE_REGISTRY="gcr.io/myrepository" federation/develop/develop.sh build_image
 $ KUBE_REGISTRY="gcr.io/myrepository" federation/develop/develop.sh push
 ```
 
-Note: This is going to overwite the values you might have set for
+Note: This is going to overwrite the values you might have set for
 `apiserverRegistry`, `apiserverVersion`, `controllerManagerRegistry` and
 `controllerManagerVersion` in your `${FEDERATION_OUTPUT_ROOT}/values.yaml`
 file. Hence, it is not recommend to customize these values in