Add new page on troubleshooting Redis connection issues

[allypascoe-aiven]

Off the back of a long, ongoing issue with Bank Jago and their Redis service, further investigations were carried out in relation to Redis connections being dropped. The investigations in question were carried out here: https://aiven.atlassian.net/browse/OPS-4106

Findings:

• The connections were getting closed because they were classed as 'idle' as no payload was being sent along to keep the connection alive.
• This was discovered after debug logging had been enabled for the service
• This was an advanced config setting the client needed to change (redis_timeout Aiven ) to increase timeout value or remove it completely

Next step:

• Create a public facing help article to share these learnings

Related Jira: https://aiven.atlassian.net/browse/SUP-689