refactor: apply feedback on migration strategy

rfc/consolidating-w3up-and-upload-service.md

@@ -40,7 +40,7 @@ We _backport_ the relevant infra changes in `upload-service-infra` that were add
 * Add the legacy Store Protocol handlers to `upload-service` by importing existing `@web3-storage/upload-api`.
 * Setup and deploy a production storage provider node that writes to carpark.
 * Migrate `allocation` table data to `blob-registry` table - this allows `space/blob/list` capability to work for older spaces.
-    * This is a simple copy of all existing rows, with a couple of field renames (`multihash` -> `digest` and `invocation` -> `cause`). For reference, I've listed the current schemas:
+    * This is a table rename and a couple of field renames (`multihash` -> `digest` and `invocation` -> `cause`). For reference, I've listed the current schemas:
         * `allocation` schema:
             * `space`: string (e.g. `did:key:space`)
             * `multihash`: string (e.g. `zQm...`)
@@ -53,7 +53,9 @@ We _backport_ the relevant infra changes in `upload-service-infra` that were add
             * `size`: number
             * `cause`: string
             * `insertedAt`: string
-* Build a maintenance mode switch to existing system allowing migration to take place without writes.
+    * We will create the new table and _temporarily_ write to both.
+    * Once deployed we'll start the migration of older data to the new table.
+    * Once the migration is completed we'll remove the old table.
 * In order to prevent confusion over what modules we're continuing to support, we will remove from the repos as much legacy code as possible.
     * Import and re-export `@storacha` equivalents of all modules. Instead of simply deleting the packages this enables us to continue to easily make and track releases (bugfixes etc.) for the legacy packages whilst still removing the majority of the code.
     * `w3up` repo changes: