Update misleading documentation information on Load Balancing

[lifetothefull]

Existing documentation URL(s)

https://developers.cloudflare.com/learning-paths/load-balancing/planning/types-load-balancers/#limitations
https://developers.cloudflare.com/load-balancing/understand-basics/session-affinity/#enabling-session-affinity-from-the-cloudflare-dashboard

What changes are you suggesting?

Matt Renn..., Cloudflare SE here. Two issues found in this documentation that are confusing one of my customers.

1. https://developers.cloudflare.com/learning-paths/load-balancing/planning/types-load-balancers/#limitations States that DNS Load balancing supports standard session affinity. DNS Load balancing does NOT support session affinity. Session affinity is greyed out when you select DNS Load Balancing. (unless I am missing something.)
2. https://developers.cloudflare.com/load-balancing/understand-basics/session-affinity/#enabling-session-affinity-from-the-cloudflare-dashboard Also has a !Important box that states "Session Affinity by Cloudflare cookie and Client IP fallback is not supported for load balancers in DNS-only mode (gray cloud)". This is implying that Session Affinity by http header and/or Cookie fallback are supported in DNS-only mode. This is also FALSE. It would be better to state "Session affinity is not supported in DNS-only mode".

Additional information

[angelampcosta]

Thanks @lifetothefull I'll track this issue in the internal ticket.