[DOCS] Add real-world breach scenario for each of the 10 starter rules #8

What to build

For each of the 10 starter scan rules, write a 2-3 sentence
real-world breach scenario explaining exactly why this
misconfiguration is dangerous and what an attacker would do with it.

Why this matters

Security rules are only useful if people understand the risk.
A concrete scenario makes the rule meaningful to developers
who aren't security experts.

Example format

AZ-STOR-001: Public blob access enabled

In 2021, a misconfigured Azure storage blob exposed 38 million
records including COVID-19 vaccination data. An attacker needs
only the storage account URL — no credentials required — to
download everything in the container.

Rules that need scenarios

• AZ-STOR-001, AZ-STOR-002
• AZ-NET-001, AZ-NET-002
• AZ-IDN-001, AZ-IDN-002
• AZ-DB-001, AZ-DB-002
• AZ-CMP-001, AZ-KV-001

Where it goes

Add to docs/adding-a-rule.md under a new section:
## Real-world impact of each rule

Branch

docs/breach-scenarios