[docs][charts] Clean up Charts docs sidebar (DX-97)

[alelthomas]

Added the Charts Accessibility page to the sidebar and did a cleanup so titles are consistent, as well as reordering the nav items alphabetically to make it easier for users to peruse.

• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

Deploy preview: https://deploy-preview-20700--material-ui-x.netlify.app/

Updated pages:

• docs/data/charts/accessibility/accessibility.md
• docs/data/charts/content-security-policy/content-security-policy.md
• docs/data/charts/data-grid-integration/data-grid-integration.md

Bundle size report

Bundle	Parsed size	Gzip size
@mui/x-data-grid	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-pro	0B(0.00%)	0B(0.00%)
@mui/x-data-grid-premium	0B(0.00%)	0B(0.00%)
@mui/x-charts	0B(0.00%)	0B(0.00%)
@mui/x-charts-pro	0B(0.00%)	0B(0.00%)
@mui/x-charts-premium	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers	0B(0.00%)	0B(0.00%)
@mui/x-date-pickers-pro	0B(0.00%)	0B(0.00%)
@mui/x-tree-view	0B(0.00%)	0B(0.00%)
@mui/x-tree-view-pro	0B(0.00%)	0B(0.00%)

Details of bundle changes

Generated by 🚫 dangerJS against b15a76a

[codspeed-hq]

CodSpeed Performance Report

Merging #20700 will not alter performance

_{Comparing alelthomas:charts-accessibility-page (b15a76a) with master (e511cfd)¹}

Summary

✅ 14 untouched

Footnotes

1. No successful run was found on master (70cac6d) during the generation of this report, so e511cfd was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩