docs: update SerpApi free searches amount in tool feature table (#32945)

**Description:** 
This PR updates the free searches per month from **100** to **250** and
renames SerpAPI to [SerpApi](https://serpapi.com/) to prevent confusion.
Add import API keys and enhance usage instructions in the Jupyter
notebook

**Issue:** N/A

**Dependencies:** N/A

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docs/scripts/tool_feat_table.py

@@ -57,8 +57,8 @@ SEARCH_TOOL_FEAT_TABLE = {
         "available_data": "URL, Snippet, Title, Search Rank, Site Links, Authors",
         "link": "/docs/integrations/tools/searchapi",
     },
-    "SerpAPI": {
-        "pricing": "100 Free Searches/Month",
+    "SerpApi": {
+        "pricing": "250 Free Searches/Month",
         "available_data": "Answer",
         "link": "/docs/integrations/tools/serpapi",
     },