[data grid][docs] Revise the Master Detail doc

[mapache-salvaje]

Part of the ongoing auditing/editing project, prioritizing Pro and Premium docs.

• changes title from "Master detail" to "Master-detail row panels"
• adds explanation of master-detail design pattern and how it relates to the Data Grid
• adds email example demo at the top
• general copyediting throughout

[mui-bot]

Deploy preview: https://deploy-preview-17927--material-ui-x.netlify.app/

Updated pages:

• docs/data/data-grid/master-detail/master-detail.md
• docs/data/data-grid/row-pinning/row-pinning.md
• docs/data/data-grid/row-recipes/row-recipes.md

Bundle size report

Total Size Change: 0B^(0.00%) - Total Gzip Change: 0B^(0.00%) Files: 120 total (0 added, 0 removed, 0 changed)

Details of bundle changes

Generated by :no_entry_sign: dangerJS against 947205f54506ae22f8846f696b8ba77203e90226

[github-actions[bot]]

Cherry-pick PRs will be created targeting branches: v7.x