Update README.md

[xlumzee]

fixed typos & grammar; AppMetrica spelling, articles

What type of PR is this?

• [ ] Refactor
• [ ] Feature
• [ ] Bug Fix
• [ ] New Query Runner (Data Source)
• [ ] New Alert Destination
• [x] Other

Description

fixed typos & grammar; AppMetrica spelling, articles

How is this tested?

• [ ] Unit tests (pytest, jest)
• [ ] E2E Tests (Cypress)
• [] Manually
• [x] N/A

Related Tickets & Documents

Mobile & Desktop Screenshots/Recordings (if there are UI changes)