TL;DR - This PR consists of fixes for broken links, broken image links, and broken Swift/Objective-C code snippets on material.io, and also adds some small copy edits.
Sometimes our documentation renders okay on GitHub, but breaks in the conversion of markdown to HTML/CSS that takes place during material.io deploys. As of yesterday, I'm able to build material.io locally, which allows me _validate_ the documentation changes I will keep making for the material.io work. It also allows me to catch broken links elsewhere, in totally unrelated files. For example, there were broken links in some Shapes documentation that were already blocking the deployment of our docs unbeknownst to us.
Closes https://github.com/material-components/material-components-ios/pull/9963
COPYBARA_INTEGRATE_REVIEW=https://github.com/material-components/material-components-ios/pull/9963 from andrewoverton:fix-formatting-issues cd54e90863274a49068e016547b1bf0b1af3afcb
PiperOrigin-RevId: 305770167
