fix: env vars from secrets and configmap + values.schema update

[PabloHiro]

This is needed because environment variables can be defined from configMaps and/or Secrets.

Example:

extraEnv:
- name: KAFKA_SSL_TRUSTSTORE_PASSWORD 
  valueFrom: 
    secretKeyRef: 
      name: apicurio 
      key: user.password

This currently fails with:

Error: values don't meet the specifications of the schema(s) in the following chart(s):
apicurio-registry:
- registry.extraEnv.0: value is required
- registry.extraEnv.0: Additional property valueFrom is not allowed

[eshepelyuk]

1. address minor comments.
2. plz add title attribute to previously added fields: initContainers, extraVolimes, extraVolumeMounts.

[eshepelyuk]

Thank you, will be abailable in 3.2.1
https://github.com/eshepelyuk/apicurio-registry-helm/releases/tag/3.2.1