suggestion: add guide on how to use the Standard Library in the browser

[iuioiua]

In other words, how to transpile and bundle code for the browser. This should:

1. Be in the README.md.
2. Include appropriate snippets using deno_emit. This may require further work in deno_emit. See Support jsr: specifiers deno_emit#167.
3. Note any considerations one must make when doing so. E.g. a source file must contain the browser-compatible declaration. See https://github.com/denoland/deno_std/blob/main/_tools/check_browser_compat.ts.

[kt3k]

I think we should recommend esbuild with esbuild-deno-loader instead of deno_emit for bundling as deno_emit is no longer actively maintained. (esbuild-deno-loader already supports jsr:)