List the Web build in the README downloads table

The v0.3.0 release now carries step-line-web-0.3.0.zip (37.5 MB, 63 MB unzipped);
downloads anonymously and serves from any static host. Docs only.

README.md

@@ -25,6 +25,7 @@ The central design goal is simple:
 | **Linux — AppImage** | [`step-line-<ver>-x86_64.AppImage`](https://git.allucanget.biz/zwitschi/security-game/releases) · single file, `chmod +x` and run |
 | **Linux — portable** | [`step-line-linux-<ver>.x86_64`](https://git.allucanget.biz/zwitschi/security-game/releases) · 64-bit, `chmod +x` and run |
 | **macOS** | [`step-line-macos-<ver>.zip`](https://git.allucanget.biz/zwitschi/security-game/releases) · unsigned build, quarantine note below |
+| **Web (browser)** | [`step-line-web-<ver>.zip`](https://git.allucanget.biz/zwitschi/security-game/releases) · unzip and serve the folder from any static host (no special headers) |
 
 **All releases:** <https://git.allucanget.biz/zwitschi/security-game/releases>