[docs] Few copy fixes

[pavan-sh]

Changes

Two small docs-only improvements:

• Update a docs script comment to use the current brand spelling (“Material UI” instead of “Material-UI”).
• Fix a grammar issue in the “Material UI is now MUI” blog post opening sentence for readability.
• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

Netlify deploy preview

https://deploy-preview-47806--material-ui.netlify.app/

Bundle size report

Bundle	Parsed size	Gzip size
@mui/material	0B(0.00%)	0B(0.00%)
@mui/lab	0B(0.00%)	0B(0.00%)
@mui/system	0B(0.00%)	0B(0.00%)
@mui/utils	0B(0.00%)	0B(0.00%)

Details of bundle changes

Generated by 🚫 dangerJS against ff4e0e2

[ZeeshanTamboli]

Thanks!

[github-actions]

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

[pavan-sh]

Thanks!

Happy to help!