Add documentation

Author: armano2

Diff for: docs/rules/use-v-on-extact.md

@@ -0,0 +1,27 @@
+# Enforce usage of `exact` modifier on `v-on`
+
+- :gear: This rule is included in `"plugin:vue/essential"`.
+
+This rule enforce usage of `exact` modifier on `v-on` when there is another `v-on` with modifier.
+
+:+1: Examples of **correct** code for this rule:
+
+```html
+<template>
+  <button @click="foo" :click="foo"></button>
+  <button v-on:click.exact="foo" v-on:click.ctrl="foo"></button>
+</template>
+```
+
+:-1: Examples of **incorrect** code for this rule:
+
+```html
+<template>
+  <button v-on:click="foo" v-on:click.ctrl="foo"></button>
+</template>
+```
+
+## Related rules
+
+- [vue/v-on-style](./v-on-style.md)
+- [vue/valid-v-on](./valid-v-on.md)