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MAY -> SHOULD for block value calculation spec

Co-authored-by: Mikhail Kalinin <noblesse.knight@gmail.com>
Co-authored-by: lightclient <14004106+lightclient@users.noreply.github.com>

src/engine/specification.md

@@ -476,14 +476,14 @@ This method follows the same specification as [`engine_forkchoiceUpdatedV1`](#en
 
 * result: `object`
   - `executionPayload`: [`ExecutionPayloadV2`](#ExecutionPayloadV2)
-  - `blockValue` : `QUANTITY`, 256 Bits - The expected value to be recieved by the `feeRecipient` in wei
+  - `blockValue` : `QUANTITY`, 256 Bits - The expected value to be received by the `feeRecipient` in wei
 * error: code and message set in case an exception happens while getting the payload.
 
 #### Specification
 
 This method follows the same specification as [`engine_getPayloadV1`](#engine_getpayloadv1) with the addition of the following:
 
-  1. Client software **MAY** use the sum of the block's priority fees or any other algorithm to determine `blockValue`.
+  1. Client software **SHOULD** use the sum of the block's priority fees or any other algorithm to determine `blockValue`.
 
 ### engine_exchangeTransitionConfigurationV1