[azure_frontdoor] Clarify supported log types in README

[navnit-elastic]

Proposed commit message

azure_frontdoor: update README to specify supported Azure Frontdoor log types.

This change updates the README to explain that the integration retrieves Access Logs (FrontDoorAccessLog) 
and Web Application Firewall Logs (FrontDoorWebApplicationFirewallLog), and clarifies that 
Activity Logs and Health Probe logs are not currently supported.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Author's Checklist

• [ ]

How to test this PR locally

Clone integrations repo.
Install elastic package locally.
Start elastic stack using elastic-package.
Move to integrations/packages/azure_frontdoor directory.
Run the following command to run tests.

elastic-package test

Related issues

• Relates [azure_frontdoor] waf ingest pipeline does not parse correctly to ECS Fields #7017

Screenshots

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Pinging @elastic/security-service-integrations (Team:Security-Service Integrations)

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🚀 Benchmarks report

To see the full report comment with /test benchmark fullreport

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: b1ad46a

cc @navnit-elastic

[elastic-vault-github-plugin-prod]

Package azure_frontdoor - 2.2.1 containing this change is available at https://epr.elastic.co/package/azure_frontdoor/2.2.1/