[Docs] LDAP Enterprise improvement (+ minor link fix)

[Isan-Rivkin]

Closes #8393

Will merge once have single approve AND no other review comments

1. Added guide for LDAP
2. Broken link fix (unrelated in external principals)

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E2E Test Results - Quickstart

[github-actions[bot]]

E2E Test Results - DynamoDB Local - Local Block Adapter