Feature docs 0.6.0

TODO:

- [x] ***Gears*** pipeline needs an example config
- [x] ***Gentrap*** refactored
- [ ] ***Toucan*** needs an disclaimer: When used with the Varda Db it assumes 2 vcf files as input
- [ ] ***Shiva*** add reference_fa to Required settings (maybe in all pipelines)
- [ ] ***Shiva*** add all variantcallers to the list of available variantcallers
- [ ] ***Shiva*** explain about public / private version of Shiva
- [ ] ***ShivaSVCalling*** 
- [ ] ***TinyCap*** add new documentation about the smallRNA pipeline.
- [x] ***Developer docs*** solves #261 - missing paragraph about the config and example code to implement using of the `config` in extensions/pipelines


Fixes #261 and #264

See merge request !315