fix: remove illegal -- from migration 0012's XML comment

Same mistake as an earlier migration this session: a literal "--" inside
an XML comment is illegal per the XML spec and crashes the entire backend
startup (Liquibase's XML parser rejects the whole changelog, not just this
file). Reworded the prose to avoid it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

fineract-provider/src/main/resources/db/changelog/tenant-store/parts/0012_seed_default_platform_api_client.xml

@@ -27,17 +27,17 @@
          #/platform-admin/menu-access works out of the box the first time the app is stood up,
          without anyone needing shell/DB access to mint the first key by hand. It is deliberately
          the SAME raw value on every deployment/tenant (requested behaviour) rather than a random
-         one generated per install -- the trade-off, on purpose: this value is visible to anyone who
-         can read this source file, exactly like a default admin password shipped in a seed script.
-         It is a bootstrap convenience, not a secret. Rotate it for any deployment that is not purely
-         local/dev: insert a new row with a real random key's hash (see ApiClientCredentialService's
-         hashing) and either deactivate or DELETE this row -- POST /v1/apiclients is intentionally
-         disabled (see ApiClientAdminApiResource), so rotation is a direct m_api_client write, same
-         as this seed.
+         one generated per install: this is a deliberate trade-off, since this value is visible to
+         anyone who can read this source file, exactly like a default admin password shipped in a
+         seed script. It is a bootstrap convenience, not a secret. Rotate it for any deployment that
+         is not purely local/dev: insert a new row with a real random key's hash (see
+         ApiClientCredentialService's hashing) and either deactivate or DELETE this row. POST
+         /v1/apiclients is intentionally disabled (see ApiClientAdminApiResource), so rotation is a
+         direct m_api_client write, same as this seed.
 
          Raw key (only shown here, since it is fixed and not a secret to rotate away from):
              cbsx_default_platform_operator_key_2026
-         api_key_hash below is SHA-256 of that exact string, hex-encoded, lowercase -- matching
+         api_key_hash below is SHA-256 of that exact string, hex-encoded, lowercase, matching
          ApiClientCredentialService#sha256Hex. -->
     <changeSet id="0012_seed_default_platform_api_client" author="cbs-nitesh">
         <preConditions onFail="MARK_RAN">