docs: sync Haystack API reference on Docusaurus

docs-website/reference/haystack-api/routers_api.md

@@ -471,21 +471,22 @@ Categorizes files or byte streams by their MIME types, helping in context-based
 
 FileTypeRouter supports both exact MIME type matching and regex patterns.
 
-For file paths, MIME types come from extensions, while byte streams use metadata.
-You can use regex patterns in the `mime_types` parameter to set broad categories
-(such as 'audio/*' or 'text/*') or specific types.
-MIME types without regex patterns are treated as exact matches.
+For file paths, MIME types come from extensions; byte streams use metadata.
+Each entry in `mime_types` is matched against a source's MIME type by exact equality first,
+falling back to regex `fullmatch` if equality misses. So `"image/svg+xml"` routes
+`image/svg+xml` streams correctly via the equality check (without `+` being interpreted as a
+regex quantifier), and patterns like `"audio/.*"` keep matching every audio subtype.
 
 ### Usage example
 
 ```python
 from haystack.components.routers import FileTypeRouter
 from pathlib import Path
 
-# For exact MIME type matching
-router = FileTypeRouter(mime_types=["text/plain", "application/pdf"])
+# Exact MIME matching — `+`-containing IANA types like image/svg+xml work correctly
+router = FileTypeRouter(mime_types=["text/plain", "application/pdf", "image/svg+xml"])
 
-# For flexible matching using regex, to handle all audio types
+# Regex matching — catch every audio subtype
 router_with_regex = FileTypeRouter(mime_types=[r"audio/.*", r"text/plain"])
 
 sources = [Path("file.txt"), Path("document.pdf"), Path("song.mp3")]