[bitnami/mysql] Improve MySQL chart comments to warn about insufficient nano and micro presets

[muthukumaran-muthiah]

Description of the change

This PR updates the comment for the resourcesPreset field in bitnami/mysql/values.yaml to explicitly state that the nano and micro presets are not recommended for MySQL due to insufficient CPU/memory for reliable startup.

Users frequently experience MySQL failing to initialize, timing out on probes, or being OOMKilled when these minimal presets are used. The updated comment provides clearer guidance and prevents confusion when these presets cause startup instability.

Benefits

• Improves accuracy and clarity of the Helm chart documentation.
• Prevents user frustration with MySQL pods that fail to start under extremely small resource presets.
• Aligns chart comments with real-world behavior and user-reported issues.
• Helps guide users toward resource levels suitable for stable MySQL deployments.

Possible drawbacks

• None to functionality.
• Users relying on nano or micro may reconsider their resource configuration, but this reflects MySQL’s actual requirements.

Additional information

• This change does not modify functionality, defaults, or resource values—only documentation.
• Maintainers have previously noted that minimal presets are primarily for lightweight containers, not complex stateful services like MySQL.
• This clarification will help new users avoid misinterpreting the preset options as all being viable for MySQL, when in practice small or higher is required for stable operation.