Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/dyn/compute_alpha.globalAddresses.html b/docs/dyn/compute_alpha.globalAddresses.html
index aab6a3c..f0fb837 100644
--- a/docs/dyn/compute_alpha.globalAddresses.html
+++ b/docs/dyn/compute_alpha.globalAddresses.html
@@ -147,7 +147,7 @@
     },
     "endTime": "A String", # [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
-    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. If creating a persistent disk snapshot, this points to the persistent disk that the snapshot was created from.
+    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. For operations related to creating a snapshot, this points to the persistent disk that the snapshot was created from.
   }</pre>
 </div>
 
@@ -172,7 +172,7 @@
       "labels": { # Labels to apply to this Address resource. These can be later modified by the setLabels method. Each label key/value must comply with RFC1035. Label values may be empty.
         "a_key": "A String",
       },
-      "networkTier": "A String", # This signifies the networking tier used for configuring this Address and can only take the following values: PREMIUM , STANDARD. If this field is not specified, it is assumed to be PREMIUM.
+      "networkTier": "A String", # This signifies the networking tier used for configuring this Address and can only take the following values: CLOUD_NETWORK_PREMIUM , CLOUD_NETWORK_STANDARD. If this field is not specified, it is assumed to be CLOUD_NETWORK_PREMIUM.
       "address": "A String", # The static external IP address represented by this resource.
       "region": "A String", # [Output Only] URL of the region where the regional address resides. This field is not applicable to global addresses.
       "users": [ # [Output Only] The URLs of the resources that are using this address.
@@ -204,7 +204,7 @@
     "labels": { # Labels to apply to this Address resource. These can be later modified by the setLabels method. Each label key/value must comply with RFC1035. Label values may be empty.
       "a_key": "A String",
     },
-    "networkTier": "A String", # This signifies the networking tier used for configuring this Address and can only take the following values: PREMIUM , STANDARD. If this field is not specified, it is assumed to be PREMIUM.
+    "networkTier": "A String", # This signifies the networking tier used for configuring this Address and can only take the following values: CLOUD_NETWORK_PREMIUM , CLOUD_NETWORK_STANDARD. If this field is not specified, it is assumed to be CLOUD_NETWORK_PREMIUM.
     "address": "A String", # The static external IP address represented by this resource.
     "region": "A String", # [Output Only] URL of the region where the regional address resides. This field is not applicable to global addresses.
     "users": [ # [Output Only] The URLs of the resources that are using this address.
@@ -263,7 +263,7 @@
     },
     "endTime": "A String", # [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
-    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. If creating a persistent disk snapshot, this points to the persistent disk that the snapshot was created from.
+    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. For operations related to creating a snapshot, this points to the persistent disk that the snapshot was created from.
   }</pre>
 </div>
 
@@ -306,7 +306,7 @@
           "labels": { # Labels to apply to this Address resource. These can be later modified by the setLabels method. Each label key/value must comply with RFC1035. Label values may be empty.
             "a_key": "A String",
           },
-          "networkTier": "A String", # This signifies the networking tier used for configuring this Address and can only take the following values: PREMIUM , STANDARD. If this field is not specified, it is assumed to be PREMIUM.
+          "networkTier": "A String", # This signifies the networking tier used for configuring this Address and can only take the following values: CLOUD_NETWORK_PREMIUM , CLOUD_NETWORK_STANDARD. If this field is not specified, it is assumed to be CLOUD_NETWORK_PREMIUM.
           "address": "A String", # The static external IP address represented by this resource.
           "region": "A String", # [Output Only] URL of the region where the regional address resides. This field is not applicable to global addresses.
           "users": [ # [Output Only] The URLs of the resources that are using this address.