docs(mariadb): name the other charts' field correctly in the issuer note

The note explaining why this chart spells the field `tls.issuer` called
the other charts' switch `tls.issuer` as well, which inverted it: it read
as though those charts use this same key to mean on/off. They spell it
`tls.enabled`.

Restore that name and hedge the claim to "some other charts". The key is
not uniformly a switch elsewhere either — one chart uses it to select
whether a hostname is added to a certificate its engine serves regardless
— so an unqualified "other charts" overstates how settled the meaning is.

Link the epic tracking the convergence of the TLS surface, so the
divergence the note describes points somewhere instead of only being
asserted.

Assisted-by: LLM
Signed-off-by: Aleksei Sviridkin <f@lex.la>

packages/apps/mariadb/README.md

@@ -80,7 +80,7 @@ The operator has no way to learn the external hostname, so verifying a connectio
 
 The default is `operator`, and it is not derived from `external`: switching issuer re-issues the server certificate under a new authority, which breaks any client that pinned the previous `ca.crt` without making anything safer — those instances already serve TLS.
 
-> The field is named for the issuer, not for on/off, because TLS is on either way. Other charts in this platform spell a similar-looking `tls.issuer` that *does* mean on/off; this one deliberately does not, and the enum makes the difference unreadable-as-a-switch.
+> The field is named for the issuer, not for on/off, because TLS is on either way. Some other charts here spell a similar-looking `tls.enabled` that *does* switch TLS on and off; this one deliberately does not, and the enum keeps it from reading as a switch. Epic [#2811](https://github.com/cozystack/cozystack/issues/2811) tracks converging the TLS surface across charts.
 
 Enforcement is separate. `tls.required: true` sets `require_secure_transport=ON` and refuses plaintext, under either issuer. It defaults to `false` because turning it on disconnects every client not yet using TLS — a decision to make once clients have the CA, not something an upgrade does.