docs: duckduckgosearch options listed (#22568)

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/utilities/duckduckgo_search.py

@@ -15,11 +15,26 @@ class DuckDuckGoSearchAPIWrapper(BaseModel):
     """
 
     region: Optional[str] = "wt-wt"
+    """
+    See https://pypi.org/project/duckduckgo-search/#regions
+    """
     safesearch: str = "moderate"
+    """
+    Options: strict, moderate, off
+    """
     time: Optional[str] = "y"
+    """
+    Options: d, w, m, y
+    """
     max_results: int = 5
-    backend: str = "api"  # which backend to use in DDGS.text() (api, html, lite)
-    source: str = "text"  # which function to use in DDGS (DDGS.text() or DDGS.news())
+    backend: str = "api"
+    """
+    Options: api, html, lite
+    """
+    source: str = "text"
+    """
+    Options: text, news
+    """
 
     class Config:
         """Configuration for this pydantic object."""