docs: create tutorial for Cosmos SDK events from existing content

[barriebyron]

Is your feature request related to a problem? Please describe. The current Cosmos SDK docs provide a conceptual overview of events https://docs.cosmos.network/master/core/events.html

However, a tutorial does not exist.

A contributor can use this content from Ethan Frey, founder of CosmWasm. @okwme recommends this content as one of the most in-depth articles on events.

We think this content is a good candidate for an easy article to add to https://tutorials.cosmos.network/.

Describe the solution you'd like to see

Turn this content into a tutorial with a user journey to help Cosmos SDK users understand events.

• Review and understand this technical content to work from: https://github.com/CosmWasm/wasmd/blob/master/EVENTS.md
• Create a new Markdown file using the https://github.com/cosmos/sdk-tutorials/blob/master/templates/tutorial_template.md

Resources:

• https://github.com/cosmos/sdk-tutorials/

Writing questions? See the excellent advice in the Google developer documentation style guide

• https://developers.google.com/style

Happy hacking!

[xavierlepretre]

The hands-on-exercise now demonstrates how to emit events and how to listen to them with CosmJS.