Update global address docs now that they are settable + ip ranges som…

…etimes (#585)

<!-- This change is generated by MagicModules. -->
Original Author: @rileykarson

website/docs/r/compute_global_address.html.markdown

@@ -66,12 +66,13 @@ The following arguments are supported:
 
 * `address` -
   (Optional)
-  The static external IP address represented by this resource.
+  The IP address or beginning of the address range represented by this
+  resource. This can be supplied as an input to reserve a specific
+  address or omitted to allow GCP to choose a valid one for you.
 
 * `description` -
   (Optional)
   An optional description of this resource.
-  Provide this property when you create the resource.
 
 * `labels` -
   (Optional, [Beta](https://terraform.io/docs/providers/google/provider_versions.html))
@@ -80,7 +81,7 @@ The following arguments are supported:
 * `ip_version` -
   (Optional)
   The IP Version that will be used by this address. Valid options are
-  IPV4 or IPV6. The default value is IPV4.
+  `IPV4` or `IPV6`. The default value is `IPV4`.
 
 * `prefix_length` -
   (Optional, [Beta](https://terraform.io/docs/providers/google/provider_versions.html))