documentation for cosmjs

[pyramation]

• [ ] https://github.com/cosmos/cosmjs/blob/main/packages/stargate/CUSTOM_PROTOBUF_CODECS.md (https://github.com/cosmos/cosmjs/issues/1313)
• [ ] https://github.com/cosmos/sdk-tutorials
• [ ] https://tutorials.cosmos.network/tutorials/6-cosmjs/5-create-custom.html
• [ ] https://github.com/cosmos/sdk-tutorials/tree/master/tutorials/6-cosmjs
• [ ] https://tutorials.cosmos.network/hands-on-exercise/3-cosmjs-adv/1-cosmjs-objects.html

[pyramation]

cc @daniel-farina we're going to update the official docs, wanted to see if you're interested to chat about this