Add helmChart target

[olblak]

This PR adds Helm Chart target support to automatically update an helm chart.
This targets works both with local files and git/github.
It supports three two scenarios:

1. We bump a value in requirements.yaml, then it deletes requirements.lock if needed, and finally bump the chartVersion
2. We bump a value in any other files but typically values.yaml, then we bump ChartVersion and the AppVersion if the flag is set to true

An example can be found here

• Add documentation on www.updatecli.io link

Signed-off-by: Olivier Vernin olivier@vernin.me