docs: update UI references to connection strings

[rodrigobnogueira]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe: Documentation update

What is the current behavior?

The current README.md instructs users to look for "URI" and "Primary Key" or "Connection string" in specific UI sections of the Azure portal. These sections change frequently and can cause confusion (as reported in Issue #254).

Issue Number: #254

What is the new behavior?

• Updates the README to use more generic instructions for finding connection details.
• Clarifies how to extract the endpoint and key from the primary connection string.
• Points users directly to official Microsoft Azure documentation, which is always up to date.

Does this PR introduce a breaking change?

• Yes
• No

Other information

Fixes #254