Do not recommend protobuf

Yet provide guide on how to use protobuf.

guides/choose-content-topic.md

@@ -14,7 +14,7 @@ The format for content topics is as follows:
 - `content-topic-name`: The actual content topic name to use for filtering.
   If your dApp uses DappConnect for several features,
   you should use a content topic per feature.
-- `encoding`: The encoding format of the message, we recommend using Protobuf: `proto`.
+- `encoding`: The encoding format of the message, Protobuf is most often used: `proto`.
 
 For example: Your dApp's name is SuperCrypto,
 it enables users to receive notifications and send private messages.

guides/relay-receive-send-messages.md

@@ -75,10 +75,12 @@ await waku.relay.send(wakuMessage);
 # Use Protobuf
 
 Sending strings as messages in unlikely to cover your dApps needs.
-To include structured objects in Waku Messages,
-we recommend you use [protobuf](https://developers.google.com/protocol-buffers/).
 
-First, let's define a data structure.
+Waku v2 protocols use [protobuf](https://developers.google.com/protocol-buffers/) [by default](https://rfc.vac.dev/spec/10/).
+
+Let's review how you can use protobuf to include structured objects in Waku Messages.
+
+First, define a data structure.
 For this guide, we will use a simple chat message that contains a timestamp and text:
 
 ```js

guides/store-retrieve-messages.md

@@ -13,7 +13,7 @@ allowing you to retrieve them at a later time.
 The Waku Store protocol is best-effort and does not guarantee data availability.
 Waku Relay should still be preferred when online;
 Waku Store can be used after resuming connectivity:
-when the dApp starts for example.
+For example, when the dApp starts.
 
 In this guide, we'll review how you can use Waku Store to retrieve messages.
 
@@ -56,9 +56,11 @@ await Promise.all(nodes.map((addr) => waku.dial(addr)));
 
 # Use Protobuf
 
-We recommend you use [protobuf](https://developers.google.com/protocol-buffers/) for messages.
+Waku v2 protocols use [protobuf](https://developers.google.com/protocol-buffers/) [by default](https://rfc.vac.dev/spec/10/).
 
-First, let's define a data structure.
+Let's review how you can use protobuf to send structured data.
+
+First, define a data structure.
 For this guide, we will use a simple news article that contains a date of publication, title and body:
 
 ```js