[docs][charts] Fix anchorEl API page

[oliviertassinari]

Fix #15575 (comment). It's a quick win, so why not. The solution is to copy https://mui.com/material-ui/api/popper/#popper-prop-anchorEl.

Before: https://master--material-ui-x.netlify.app/x/api/charts/charts-tooltip/#props

After. https://deploy-preview-15625--material-ui-x.netlify.app/x/api/charts/charts-tooltip/#props

[mui-bot]

Deploy preview: https://deploy-preview-15625--material-ui-x.netlify.app/

Generated by 🚫 dangerJS against 067dce6

[codspeed-hq]

CodSpeed Performance Report

Merging #15625 will improve performances by 36.63%

_{Comparing oliviertassinari:chart-fix-anchor-el-docs (067dce6) with master (ee6ee3e)}

Summary

⚡ 1 improvements
✅ 5 untouched benchmarks

Benchmarks breakdown

	Benchmark	master	oliviertassinari:chart-fix-anchor-el-docs	Change
⚡	ScatterChartPro with big data amount	173.6 ms	127 ms	+36.63%

[oliviertassinari]

The performance benchmark run in dev mode, shouldn't we move this to be with process.env.NODE_ENV = production?

https://codspeed.io/mui/mui-x/branches/oliviertassinari:chart-fix-anchor-el-docs

Oh wait, it doesn't run in a real browser but in jsdom. Hum, OK, results won't be super helpful.

[JCQuintas]

The performance benchmark run in dev mode, shouldn't we move this to be with process.env.NODE_ENV = production?

https://codspeed.io/mui/mui-x/branches/oliviertassinari:chart-fix-anchor-el-docs

Oh wait, it doesn't run in a real browser but in jsdom. Hum, OK, results won't be super helpful.

It runs on our built version, but I suppose I didn't make the jsdom run using production mode 🤔

But indeed, the goal is mainly to see in case we make mistakes or improvements. They are not meant to represent "how fast the charts are", but "how versions speeds compare"

[oliviertassinari]

@JCQuintas Right, yeah, we will get some directional indicators from those benchmark assertions 👍. However, we can't base merge or tradeoff decisions based on them. A change could be slower in jsdom but faster in a real browser, it could be slower in dev mode, but faster in prod mod.