feat(helm-charts): initialize helm repository

[tthvo]

Depends on cryostatio/cryostat-helm#71

Will need to update to point to correct commit hash when above PR is merged.

How to test

# Checkout this PR head ref
# Fetch submodule
$ git submodule update --remote # For now

# Launch the local web server for upstream docs
$ bundle exec jekyll serve --watch --livereload --open-url --future \
--config _config.yml,_config-dev.yml

# Add a helm repo (i.e. our web server)
$ helm repo add local http://127.0.0.1:4000/helm-charts

# Update helm charts information locally if needed
$ helm repo update

# Search for Cryostat helm chart
$ helm search repo cryostat
NAME          	CHART VERSION	APP VERSION	DESCRIPTION                                       
local/cryostat	0.3.0        	2.3.0      	Securely manage JFR recordings for your contain...