add template annotation support for sts/deploy to allow linkerd or ot…

[darkn3rd]

This adds support for deploy and sts template annotations. This will allow for annotations that allow services to inject side-cars containers, such as linkerd proxy-injection.

This changes were added:

• ratel.extraAnnotations for deploy template annotations
• alpha.extraAnnotations and zero.extraAnnotations for sts template annotations
• updated README for new value and missing metrics.enabled value
• provided example linkerd.yaml

This was tested with the following values file:

alpha:
  extraAnnotations:
    config.linkerd.io/skip-inbound-ports: 7080
    config.linkerd.io/skip-outbound-ports: 7080
    linkerd.io/inject: enabled
zero:
  extraAnnotations:
    config.linkerd.io/skip-inbound-ports: 5080
    config.linkerd.io/skip-outbound-ports: 5080
    linkerd.io/inject: enabled
ratel:
  enabled: true
  extraAnnotations:
     linkerd.io/inject: enabled

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This change is 

[danielmai]

Reviewed 6 of 6 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @darkn3rd)

[danielmai]

Thanks for the PR @darkn3rd!