fix: made the startup probe consistent for nodespec and druidspec

[avtarOPS]

Fixes #119

Description

Made the spelling of startup probe config consistent for nodeSpec and druidSpec.

This PR has:

• been tested on a real K8S cluster to ensure creation of a brand new Druid cluster works.
• been tested for backward compatibility on a real K*S cluster by applying the changes introduced here on an existing Druid cluster. If there are any backward incompatible changes then they have been noted in the PR description.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added documentation for new or modified features or behaviors.

---

Key changed/added files in this PR

• apis/druid/v1alpha1/druid_types.go
• apis/druid/v1alpha1/zz_generated.deepcopy.go
• chart/templates/crds/druid.apache.org_druids.yaml
• config/crd/bases/druid.apache.org_druids.yaml
• config/druid.apache.org_druids.yaml
• controllers/druid/handler.go
• docs/api_specifications/druid.md
• e2e/configs/druid-mmless.yaml
• examples/tiny-cluster-mmless.yaml

[SatyaKuppam]

Is this change backwards compatible?

• What will happen to existing clusters that have startUpProbes in them when we upgrade?
• Should we expect them to start failing?

[AdheipSingh]

@SatyaKuppam
Change is not backward compatible, any change in CR spec is not backward compatible. ( unless there are conversion webhooks )

• Pls change your CR, to add startUpProbe

To do such changes, you should

• Scale down operator to zero
• Apply or edit CR with startUpProbe
• Upgrade operator version.

This way the current state remains as it is. Nodes should not restart.

Ill try to document this. Thanks for asking this question.