Dev Docs: P2P feefilter: add extra details

- Add annotated hex example

- Add search box entry and autocrossref entry

- Add Bitcoin Core 0.12/0.13 cross links

_autocrossref.yaml

@@ -27,6 +27,8 @@ DER-formatted: der
 ECDSA:
 epoch time: unix epoch time
 '`expires`': pp expires
+'`feefilter` message': feefilter message
+'`feefilter` messages': feefilter message
 fiat:
 '`filteradd` message': filteradd message
 '`filteradd` messages': filteradd message

_config.yml

@@ -532,6 +532,7 @@ devsearches:
     - "addr":  "/en/developer-reference#addr"
     - "alert":  "/en/developer-reference#alert"
     - "block": "/en/developer-reference#block"
+    - "feefilter": "/en/developer-reference#feefilter"
     - "filteradd": "/en/developer-reference#filteradd"
     - "filterclear": "/en/developer-reference#filterclear"
     - "filterload": "/en/developer-reference#filterload"

_includes/devdoc/ref_p2p_networking.md

@@ -803,8 +803,8 @@ The `feefilter` message is a request to the receiving peer to not relay any
 transaction inv messages to the sending peer where the fee rate for the
 transaction is below the fee rate specified in the feefilter message.
 
-`feefilter` was introduced in V0.13.0 following the introduction
+`feefilter` was introduced in Bitcoin Core 0.13.0 following the introduction
-of mempool limiting in V0.12.0. Mempool limiting provides protection against
+of mempool limiting in Bitcoin Core 0.12.0. Mempool limiting provides protection against
 attacks and spam transactions that have low fee rates and are unlikely to be
 included in mined blocks. The `feefilter` messages allows a node to inform its
 peers that it will not accept transactions below a specified fee rate into
@@ -813,7 +813,7 @@ transactions below that fee rate to that node.
 
 | Bytes | Name    | Data Type | Description
 |-------|---------|-----------|---------------
-| 8     | feerate | uint64_t  | The fee rate (in Satoshis per kilobyte) under which transactions should not be relayed to this peer.
+| 8     | feerate | uint64_t  | The fee rate (in satoshis per kilobyte) below which transactions should not be relayed to this peer.
 
 The receiving peer may choose to ignore the message and not filter transaction
 inv messages.
@@ -831,8 +831,16 @@ if they are below the feefilter fee rate.
 
 inv messages generated from a mempool message are subject to a fee filter if it exists.
 
+The annotated hexdump below shows a `feefilter` message. (The message
+header has been omitted.)
+
 {% endautocrossref %}
 
+{% highlight text %}
+7cbd000000000000 ... satoshis per kilobyte: 48,508
+{% endhighlight %}
+
+
 #### FilterAdd
 {% include helpers/subhead-links.md %}
 

_includes/references.md

@@ -180,6 +180,7 @@ http://opensource.org/licenses/MIT.
 [addr message]: /en/developer-reference#addr "The P2P network message which relays IP addresses and port numbers of active nodes to other nodes and clients, allowing decentralized peer discovery."
 [alert message]: /en/developer-reference#alert "The P2P network message which sends alerts in case of major software problems."
 [block message]: /en/developer-reference#block "The P2P network message which sends a serialized block"
+[feefilter message]: /en/developer-reference#feefilter "The P2P network message which requests the receiving peer not relay any transactions below the specified fee rate"
 [filteradd message]: /en/developer-reference#filteradd "A P2P protocol message used to add a data element to an existing bloom filter."
 [filterclear message]: /en/developer-reference#filterclear "A P2P protocol message used to remove an existing bloom filter."
 [filterload message]: /en/developer-reference#filterclear "A P2P protocol message used to send a filter to a remote peer, requesting that they only send transactions which match the filter."