docs: Update security docs to reflect LDAP casing issues

[andersbogsnes]

Description

The docs currently do not mention that LDAP AUTH_ROLES_MAPPINGS are case-sensitive. This PR adds a line to document this.

Fixes #1641

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 #2098 (101a499) into master (8203783) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2098      +/-   ##
==========================================
- Coverage   79.31%   79.30%   -0.02%     
==========================================
  Files          72       72              
  Lines        8970     8970              
==========================================
- Hits         7115     7114       -1     
- Misses       1855     1856       +1     

Flag	Coverage Δ
python	79.30% <ø> (-0.02%)	⬇️

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see 1 file with indirect coverage changes