Chapter 1 content updates: use case section added; Keplr wallet setup and ecosystem stats revised

[AndrewB9lab]

Documentation content update for Chapter 1, Sections 2/3/4

This PR includes the following changes to Chapter 1:

• Revised ecosystem statistics and tone boosting for the interchain
• Updated Keplr wallet setup process and screenshots
• Addition of a new Use Case section
• Also minor edits to readme and Ch1 index to add Use Case section into the program structure

Change scope

The changes in this Pull Request include (please tick all that apply):

• [ ] Small language/grammar fixes
• [X] Small content fixes
• [X] Addition of new content
• [ ] Sample code/command updates
• [ ] Platform fixes
• [ ] Other

[netlify[bot]]

✅ Deploy Preview for cosmos-ida-portal ready!

Name	Link
🔨 Latest commit	b8805e8f2b22a8f7a94e231c0d4390e99850328e
🔍 Latest deploy log	https://app.netlify.com/sites/cosmos-ida-portal/deploys/653aac90b389dd000848914b
😎 Deploy Preview	https://deploy-preview-26--cosmos-ida-portal.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify[bot]]

✅ Deploy Preview for cosmos-developer-portal ready!

Name	Link
🔨 Latest commit	b8805e8f2b22a8f7a94e231c0d4390e99850328e
🔍 Latest deploy log	https://app.netlify.com/sites/cosmos-developer-portal/deploys/653aac9090e63d00087d2d57
😎 Deploy Preview	https://deploy-preview-26--cosmos-developer-portal.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.