Feat: Document slash rejection, update normalization rules

README.md

@@ -44,15 +44,24 @@ All queries are normalized before caching and searching:
 | Multiple spaces collapsed | `orange++cat` | `orange cat` |
 | Trailing slashes stripped | `orange+cat/` | `orange cat` |
 | Control characters removed | `orange\x00cat` | `orangecat` |
+| **Slashes rejected** | `wp-admin/setup.php` | `bad.webp` served |
 | **Max length: 200 characters** | — | 400 error if exceeded |
 
 ### Characters that work fine
 
 - **Letters, numbers, spaces** — standard queries
 - **Hyphens** (`spider-man`), **dots** (`node.js`), **apostrophes** (`90's`) — passed through
-- **Slashes** (`AC/DC`) — kept as-is in the normalized query
 - **Unicode** (`café`, `日本`) — supported via URL encoding
 
+### Slashes must be encoded
+
+Literal slashes (`/`) in the URL path are **rejected** to prevent bot abuse (e.g. `wp-admin/setup-config.php` probes). If your query genuinely contains a slash, encode it as `%2F`:
+
+| Query | URL |
+|---|---|
+| AC/DC | `/AC%2FDC` ✅ |
+| AC/DC | `/AC/DC` ❌ (rejected) |
+
 ### Things to know
 
 - **Query parameters (`?...`)** are ignored — `/orange+cat?size=large` → `orange cat`