use better deprecation message

Author: Steve Szyszkiewicz

docs/src/data/endpoints/linodes.yaml

@@ -53,6 +53,7 @@ endpoints:
               The Distribution to deploy this Linode with.  May not be included
               if 'backup_id' or 'image' is sent.
             type: String
+            deprecated: This parameter will be deprecated once APIv4 out of beta. See changelog for more information.
           root_pass:
             optional: unless source == "distro"
             description: >
@@ -195,7 +196,8 @@ endpoints:
               Optional distribution to deploy with this disk.
               <ul><li>If no distribution is provided, a blank disk
               is created.</li></ul> You may not provide distribution if image is provided.
-            type: Distribution
+            type: String
+            deprecated: This parameter will be deprecated once APIv4 out of beta. See changelog for more information.
           image:
             optional: true
             description: >
@@ -1009,10 +1011,11 @@ endpoints:
         dangerous: true
         params:
           distribution:
+            optional: true
             description: >
                 An ID of a Distribution to deploy to this Linode.
             type: String
-            deprecated: Some deprecated stuff
+            deprecated: This parameter will be deprecated once APIv4 out of beta. See changelog for more information.
           image:
             optional: true
             description: >

docs/src/data/objects/linode.yaml

@@ -77,6 +77,7 @@ schema:
     type: Distribution
     seeAlso: "/reference/endpoints/linode/distributions"
     filterable: true
+    deprecated: This parameter will be deprecated once APIv4 out of beta. See changelog for more information.
   group:
     editable: true
     type: String