Improve sentence structure in README.md

[retr0verride]

Replaced a period with a semicolon for better sentence flow.

Description

Fixes # (issue)

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that causes existing functionality to change)
• Refactor (no functional change — code quality / structure improvement)
• Documentation / chore

Checklist

Code quality

• ruff passes with no errors (run via pre-commit run ruff)
• mypy --strict passes for all changed files under domain/, application/, infrastructure/
• bandit reports no new HIGH/MEDIUM findings
• New logic is covered by unit tests (≥80% branch coverage maintained)
• Cyclomatic complexity of changed functions ≤ 10

Security

• No secrets, tokens, or credentials committed (gitleaks clean)
• All new network-facing inputs are validated at the system boundary
• No new bare except: or except Exception: pass clauses
• If iptables rules are modified: net-admin privilege is the minimum required

Domain integrity

• Domain layer (domain/) imports nothing from infrastructure/ or gui/
• Application layer imports only domain/ ports
• New exceptions inherit from domain.exceptions.NotTheNetError

Tests

• Unit tests added / updated
• If Kali-only behaviour: guarded with @pytest.mark.kali or test_kali_fidelity.py
• CI passes locally: pytest --cov --cov-fail-under=80

Documentation

• CHANGELOG.md entry added under [Unreleased] (Conventional Commits format)
• docs/ updated if public-facing behaviour changed
• openapi.yaml updated if health API changed

Breaking changes

N/A

Deployment notes

N/A