docs/readme: README still shows ./shellforge commands in CLI reference table (PR #29 partial fix)

[jpleva91]

Inconsistency: CLI table uses ./shellforge prefix

PR #29 fixes the quick-start section and PR #46 fixes docs/index.html, but the CLI reference table in README.md still uses the old ./shellforge prefix for every command:

| `./shellforge qa` | Run the QA agent |
| `./shellforge report` | Run the report agent |
| `./shellforge agent` | Run a custom agent |
| `./shellforge scan [dir]` | Run security scan |

For users who install via Homebrew (brew install shellforge) there is no ./ prefix — shellforge is on their PATH. The inconsistency is confusing.

The printUsage() function in cmd/shellforge/main.go and the quick-start block in PR #46 both correctly omit the ./ prefix. The CLI table should match.