Document new API and deprecate old

[alanshaw]

In #591 we switched to a new simplier API with new packages. Due to time constraints we didn't document the new packages or deprecate the old packages yet (they still work but with older versions of w3up).

cc @travis

[Honour-d-dev]

 ⨯ node_modules\@w3ui\react\build\esm\index.js (17:7) @ commonjsRequire
 ⨯ unhandledRejection: Error: Could not dynamically require "url". Please configure the dynamicRequireTargets or/and ignoreDynamicRequires option of @rollup/plugin-commonjs appropriately for this require call to work.
    at commonjsRequire (webpack-internal:///(ssr)/./node_modules/@w3ui/react/build/esm/index.js:40:11)
    at __wbg_init (webpack-internal:///(ssr)/./node_modules/@w3ui/react/build/esm/index.js:18202:124)
    at eval (webpack-internal:///(ssr)/./node_modules/@w3ui/react/build/esm/index.js:18236:21)
    at eval (webpack-internal:///(ssr)/./node_modules/@w3ui/react/build/esm/index.js:47:9)
    at eval (webpack-internal:///(ssr)/./node_modules/@w3ui/react/build/esm/index.js:48:7)
    at eval (webpack-internal:///(ssr)/./node_modules/@w3ui/react/build/esm/index.js:29511:3)

code runs fine on the browser without errors after @rollup config but still throws on terminal and during build. this is with the new w3ui api

[Honour-d-dev]

its also possible i didn't do the rollup configuration right, so perhaps an example on that would be appreciated
my config

import commonjs from "@rollup/plugin-commonjs";

export default {
  input: "src/index.js",
  output: {
    dir: "output",
    format: "cjs",
  },
  plugins: [
    commonjs({
      dynamicRequireTargets: ["node_modules/@w3ui/*.js"],
      ignoreDynamicRequires: true,
      strictRequires: true,
    }),
  ],
};