Merge branch 'master' into 'master'

fix Mumble link (removing the space between ']' & '(' )

See merge request Teckids/team-foss/schul-frei/schul-frei.org!2

content/posts/en/2020-03-15_corona.md

@@ -157,7 +157,7 @@ A Teckids account is not necessary.
 Yes, you need to install additional software. But this is Free and
 gratis and is available from the normal package systems for Linux
 distributions, from various app Stores or alternatively can be
-downloaded direct from the [Mumble website] (https://www.mumble.info/)
+downloaded direct from the [Mumble website](https://www.mumble.info/)
 and then installed.
 
 #### Can I create my own conference rooms?