Update AZ400_M05_L10_Integrating_Azure_Key_Vault_with_Azure_DevOps.md

[yashints]

Added a missing step to enable the admin user first before copying the password value

Related Issue

Link related Github Issue 🢂 Fixes #554

Checklist

Mark completed with "x" between brackets, "[x]", or checking the box once the PR is created:

• [X] Has related GitHub Issue 💥 Create Issue 📝
• [X] Tested it
• [X] Read the PR collaboration guide 👓 Collaboration Guide 📝

Changes proposed in this pull request:

• Adding a note to enable Admin user first

[LuizMacedo]

Thanks @yashints!