Update the HA NFS docs

What does this MR do?

Updates the NFS HA documentation to align with the git_data_dirs legacy configuration being deprecated in 11.0.

Used the storage configuration documentation as a guide.

Author's checklist

• Apply the correct labels and milestone
• Crosslink the document from the higher-level index
• Crosslink the document from other subject-related docs

Review checklist

• Your team's review (required)
• PM's review (recommended, but not a blocker)
• Technical writer's review (required)
• Merge the EE-MR first, CE-MR afterwards