Remove website integration notes

integrate.md

-* i18n: the form is already configured to use the `lang` tag of the mounting
-  dom element, so if we set that from the website, we should be fine.
-* only show the LocaleSwitcher in dev mode
-
-### bundling
-
-* The built-in bundler (esbuild) of snowpack creates inline style elements
-  dynamically, which the CSP doesn't allow. Better CSS support in esbuild is
-  underway but not finished.
-* There is a experimental @snowpack/plugin-optimize plugin which has a
-  preloadCSS option to gather all css into one file. That part works, but this
-  plugin doesn't allow bundling the javascript parts, and the unbundled script
-  files it outputs give errors in my browser.
-* The recommended (by snowpack authors) approach is to use
-  @snowpack/plugin-webpack, but webpack errors out on the current source code.
-  * https://github.com/snowpackjs/snowpack/discussions/2218 : add core-js as dev dependency
-  * add browserslist to package.json
-* After fixing above errors, with some effort I could load the contact form on the website.
-  * However, the "urgent request" button doesn't have the effect it should
-    have, of removing the regular submit button from the DOM, and creating the
-    special urgent request submit button and text field. I checked, and the
-    `setUrgentIntent` function does get called, so maybe the code that listens
-    for that intent is not loaded for some reason?
-* Replace snowpack by webpack
-  * testing: http://www.thedreaming.org/2020/11/09/jest-for-web-projects/
-
-## TODO
-
-* load fonts from website, or not at all