Explain HBA rules in their field description

[cbandy]

Checklist:

• Have you added an explanation of what your changes do and why you'd like them to be included?
• Have you updated or added documentation for the change, as applicable?
• Have you tested your changes on all related environments with successful results, as applicable?
  • Have you added automated tests?

Type of Changes:

• Documentation

What is the current behavior (link to any open issues here)?

These fields have no description at all.

What is the new behavior (if this is a feature change)?

$ kubectl explain PostgresCluster.spec.authentication.rules

GROUP:      postgres-operator.crunchydata.com
KIND:       PostgresCluster
VERSION:    v1beta1

FIELD: rules <[]Object>


DESCRIPTION:
    Postgres compares every new connection to these rules in the order they are
    defined. The first rule that matches determines if and how the connection
    must then authenticate. Connections that match no rules are disconnected.
    
    When this is omitted or empty, Postgres accepts encrypted connections to any
    database from users that have a password. To refuse all network connections,
    set this to one rule that matches "host" connections to the "reject" method.
    
    More info: https://www.postgresql.org/docs/current/auth-pg-hba-conf.html
    
FIELDS:
  connection	<string>
    The connection transport this rule matches. Typical values are:
     1. "host" for network connections that may or may not be encrypted.
     2. "hostssl" for network connections encrypted using TLS.
     3. "hostgssenc" for network connections encrypted using GSSAPI.

  databases	<[]string>
    Which databases this rule matches. When omitted or empty, this rule matches
    all databases.

  hba	<string>
    One line of the "pg_hba.conf" file. Changes to this value will be
    automatically reloaded without validation.

  method	<string>
    The authentication method to use when a connection matches this rule.
    The special value "reject" refuses connections that match this rule.
    
    More info: https://www.postgresql.org/docs/current/auth-methods.html

  options	<map[string]Object>
    Additional settings for this rule or its authentication method.

  users	<[]string>
    Which user names this rule matches. When omitted or empty, this rule matches
    all users.

Other Information:

Issue: PGO-2263

[cbandy]

I created https://issue.k8s.io/130946 for that options <map[string]Object>.

[tony-landreth]

Looks good!