ux(docs): enable eslint rule key-spacing

.eslintrc.cjs

@@ -17,7 +17,6 @@ module.exports = {
     {
       files: ['**/*.md/*.@(mjs|ts)'],
       rules: {
-        'key-spacing': 'off',
         'max-statements-per-line': 'off',
         'no-multi-spaces': 'off',
         'no-undef': 'off',

README.md

@@ -524,7 +524,7 @@ Each handler is called not only with the given arguments but also with the curre
 stopPropagation = function(ev) { ev.stopPropagation() }
 sendValue = function(func, ev, vnode) { func(vnode.elm.value) }
 
-h('a', { on:{ click:[[sendValue, console.log], stopPropagation] } });
+h('a', { on: { click: [[sendValue, console.log], stopPropagation] } });
 ```
 
 Snabbdom allows swapping event handlers between renders. This happens without