convert all [[app.id]] links to https://f-droid.org/packages/app.id/

fdroidserver#845
fdroidclient#1000
jekyll-fdroid!60

```
sed -i 's,\[\[\([^ :]*\)\]\],https://f-droid.org/packages/\1,g' metadata/*.yml metadata/*/*/description.txt
```
parent 16d7661c
Pipeline #217628334 passed with stage
in 91 minutes and 8 seconds