Merge pull request #6 from HowdyHub/5-add-type-attribute-to-menu-button

[#5] Add missing 'type' attribute to menu buttons.

Author: hubgit

react-prosemirror/src/MenuBar.js

@@ -6,6 +6,7 @@ import classes from './MenuBar.module.css'
 const Button = (state, dispatch) => (item, key) => (
   <button
     key={key}
+    type="button"
     className={classnames({
       [classes.button]: true,
       [classes.active]: item.active && item.active(state)