[web-client] simple theme: build & development env based on vite.

Vite is a build tool, it consists of two major parts [1]:

- A dev server that provides rich feature enhancements over native ES modules,
  for example extremely fast Hot Module Replacement (HMR).

- A build command that bundles your code with Rollup, pre-configured to output
  highly optimized static assets for production.

[1] https://vite.dev/guide/

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

client/simple/README.rst

@@ -0,0 +1,24 @@
+=====================
+MEMO vite development
+=====================
+
+Local install::
+
+  # in folder ./client/simple/
+  $ npm install
+
+Start development server::
+
+  $ ./manage vite.simple.dev
+
+  # in folder ./client/simple/
+  $ npm exec -- vite
+
+Fix source code::
+
+  # in folder ./client/simple/
+  $ npm run fix
+
+Fix & Build::
+
+  $ ./manage vite.simple.build