Sample documentation giving syntax error in IE11

[rinobatin]

Opening https://vueds.com/example/ in IE11 results to

which points to the this arrow function

[lukenofurther]

This error first appears in release 3.5.6 and is caused by vue-styleguidist updates.

vue-styleguidist/vue-styleguidist#251

I've implemented the fix @elevatebart suggests in that issue here - #180