feat(zoom-image): add plugin

src/plugins/zoom-image.js

@@ -0,0 +1,23 @@
+import zoom from 'zoom-image'
+import style from 'zoom-image/css/zoom-image.css'
+
+function install (hook) {
+  const dom = Docsify.dom
+  let destroys
+
+  // add style
+  dom.appendTo(dom.head, dom.create('style', style))
+
+  hook.doneEach(_ => {
+    const images = dom.findAll('img:not(.emoji)')
+
+    if (Array.isArray(destroys) && destroys.length) {
+      destroys.forEach(o => o())
+      destroys = []
+    }
+
+    destroys = images.map(zoom)
+  })
+}
+
+$docsify.plugins = [].concat(install, $docsify.plugins)