Copy edit to NIM NAP WAF docs

[travisamartin]

Proposed changes

This PR:

• Expires the WAF Configuration Management topic
• Renames the following topics
  • NGINX App Protect WAF configuration management --> How WAF policy management works
  • Manage Your App Protect WAF Configs --> Set up WAF configuration management
  • Manage WAF Security Policies and Security Log Profiles --> Manage and deploy WAF policies and log profiles
• Copy edits for style, audience, and reading level

[github-actions]

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[mjang]

Love it! (I've added some minor comments for consistency)

For future discussion, should we think about harmonizing terms between NIM and N1C, such as

NIM "Instance Groups" ~ N1C "Config Sync Groups"

[mjang]

I did a Vale-based Flesch-Kincaid comparison for the manage-waf-security-policies.md file

Before (current main): 9.51
After (with this PR): 7.45