Completed Wasmd chapter.

Author: DariuszDepta

docs/ibc/_category_.json

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+{
+  "label": "IBC",
+  "position": 4,
+  "link": {
+    "type": "doc",
+    "id": "introduction"
+  }
+}

docs/ibc/introduction.md

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+# Introduction
+
+IBC is a standard that defines how blockchains can send and receive messages to each other.
+This allows for the creation of a network of blockchains that can interact with each other.
+
+You can use the IBC protocol as a building block to create your own custom protocols on top of it,
+but you can also use existing protocols like the [ICS-20 token transfer protocol]. In the following
+sections, we will explain how both of these work. Using CosmWasm for this gives you a key advantage
+over writing a custom Cosmos SDK module in Go: you can easily deploy and upgrade your contract
+without having to go through a full chain upgrade (on multiple chains, mind you).
+
+[ICS-20 token transfer protocol]: https://github.com/cosmos/ibc/blob/main/spec/app/ics-020-fungible-token-transfer/README.md