fix(docs): updated to use defineBoot

Author: hawkeye64

docs/src/pages/all-about-qmarkdown/installation-types.md

@@ -89,22 +89,22 @@ $ npm install @quasar/quasar-ui-qmarkdown
 Then
 
 ```js
-import { boot } from 'quasar/wrappers'
+import { defineBoot } from 'quasar/wrappers'
 import Plugin from '@quasar/quasar-ui-qmarkdown'
 import '@quasar/quasar-ui-qmarkdown/dist/index.css'
 
-export default boot(({ app }) => {
+export default defineBoot(({ app }) => {
   app.use(Plugin)
 })
 ```
 
 or from sources
 
 ```js
-import { boot } from 'quasar/wrappers'
+import { defineBoot } from 'quasar/wrappers'
 import Plugin from '@quasar/quasar-ui-qmarkdown/src/QMarkdown.js'
 
-export default boot(({ app }) => {
+export default defineBoot(({ app }) => {
   app.use(Plugin)
 })
 ```