Add descriptions to docs pages

[tembo]

Summary

Added description metadata to multiple documentation pages across features and integrations sections to improve SEO and provide quick page summaries.

Changes

• Added concise descriptions to MDX files in:
  • features/ directory
  • integrations/ directory
• Fixed icon formatting for some integration pages
• Descriptions provide a clear, one-sentence overview of each feature/integration

Notes

• Descriptions are under 160 characters for optimal SEO
• Maintained existing content and structure of pages

Want tembo to make any changes? Add a review or comment with @tembo and i'll get back to work!

[tembo]

Requesting review from @ryw who has experience with the following files modified in this PR:

• integrations/aws.mdx
• integrations/jira.mdx
• integrations/slack.mdx
• integrations/github.mdx
• integrations/gitlab.mdx
• features/automations.mdx
• integrations/postgres.mdx
• features/coding-agents.mdx
• features/sandbox-environment.mdx