docs: Updated LDAP Documentation

[a-gerhard]

Description

After spending some time trying to set up Apache Airflow with LDAP-over-TLS authentication and running into multiple TLS issues, I added some missing documentation that would helped me.

ADDITIONAL INFORMATION

• Has associated issue:
• Is CRUD MVC related.
• Is Auth, RBAC security related.
• Changes the security db schema.
• Introduces new feature
• Removes existing feature

[codecov]

Codecov Report

Merging #1988 (967d66e) into master (57e9d10) will decrease coverage by 33.24%.
The diff coverage is n/a.

❗ Current head 967d66e differs from pull request most recent head d7f5c42. Consider uploading reports for the commit d7f5c42 to get more accurate results

@@             Coverage Diff             @@
##           master    #1988       +/-   ##
===========================================
- Coverage   78.10%   44.87%   -33.24%     
===========================================
  Files          71       71               
  Lines        8611     8479      -132     
===========================================
- Hits         6726     3805     -2921     
- Misses       1885     4674     +2789     

Flag	Coverage Δ
python	44.87% <ø> (-33.24%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
flask_appbuilder/security/sqla/apis/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
flask_appbuilder/security/sqla/apis/role/schema.py	0.00% <0.00%> (-100.00%)	⬇️
flask_appbuilder/security/sqla/apis/user/schema.py	0.00% <0.00%> (-100.00%)	⬇️
...ask_appbuilder/security/sqla/apis/role/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
...ask_appbuilder/security/sqla/apis/user/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
...ask_appbuilder/security/sqla/apis/view_menu/api.py	0.00% <0.00%> (-100.00%)	⬇️
...sk_appbuilder/security/sqla/apis/permission/api.py	0.00% <0.00%> (-100.00%)	⬇️
...sk_appbuilder/security/sqla/apis/user/validator.py	0.00% <0.00%> (-100.00%)	⬇️
...ppbuilder/security/sqla/apis/view_menu/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
...pbuilder/security/sqla/apis/permission/__init__.py	0.00% <0.00%> (-100.00%)	⬇️
... and 46 more

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[dpgaspar]

Thank you!

left just a really small comment

[dpgaspar]

File must be PEM-encoded (change the upper I)