Fix wording nits

As suggested by @rustyrussell

04-onion-routing.md

@@ -256,8 +256,6 @@ The creator of `encrypted_recipient_data` (usually, the recipient of payment):
 
 The writer of `tlv_payload`:
 
-  - Unless `node_announcement`, `init` message or the [BOLT #11](11-payment-encoding.md#tagged-fields) offers feature `var_onion_optin`:
-    - MUST use the legacy payload format instead.
   - For every node inside a blinded route:
     - MUST include the `encrypted_recipient_data` provided by the recipient
     - For the first node in the blinded route:
@@ -298,10 +296,9 @@ The reader:
         - the amount is below `encrypted_recipient_data.payment_constraints.htlc_minimum_msat`.
     - If `allowed_features` is missing:
       - MUST process the message as if it were present and contained an empty array.
-    - If `allowed_features` is present:
-      - MUST return an error if:
-        - `encrypted_recipient_data.allowed_features.features` contains an unknown feature bit (even if it is odd).
-        - the payment uses a feature not included in `encrypted_recipient_data.allowed_features.features`.
+    - MUST return an error if:
+      - `encrypted_recipient_data.allowed_features.features` contains an unknown feature bit (even if it is odd).
+      - the payment uses a feature not included in `encrypted_recipient_data.allowed_features.features`.
     - If it is not the final node:
       - MUST return an error if the payload contains other tlv fields than `encrypted_recipient_data` and `current_blinding_point`.
       - MUST return an error if `encrypted_recipient_data` does not contain either `short_channel_id` or `next_node_id`.
@@ -1256,7 +1253,7 @@ reasonable time.
 2. data:
    * [`sha256`:`sha256_of_onion`]
 
-The onion sent to a blinded path didn't match the recipient's encrypted relay requirements.
+An error occurred within the blinded path.
 
 ### Requirements