Remove link to Promscale

[ramonguiu]

Signed-off-by: Ramon Guiu ramon@timescale.com

What this PR does / why we need it

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer

Checklist

• [ ] Chart Version bumped
• [ ] CLA signed