Add docs to enable SearchApi engines for web search on OpenUI

Add screenshots to explain the steps

docs/tutorial/web_search.md

@@ -179,6 +179,27 @@ You will have to explicitly toggle this On/Off in a chat.
 
 This is enabled on a per session basis eg. reloading the page, changing to another chat will toggle off.
 
+## SearchApi API
+
+[SearchApi](https://searchapi.io) is a collection of real-time SERP APIs. Any existing or upcoming SERP engine that returns `organic_results` is supported. The default web search engine is `google`, but it can be changed to `bing`, `baidu`, `google_news`, `bing_news`, `google_scholar`, `google_patents`, and others.
+
+### Setup
+
+1. Go to [SearchApi](https://searchapi.io), and log on or create a new account.
+2. Go to `Dashboard` and copy the API key.
+3. With `API key`, open `Open WebUI Admin panel` and click `Settings` tab, and then click `Web Search`.
+4. Enable `Web search` and set `Web Search Engine` to `searchapi`.
+5. Fill `SearchApi API Key` with the `API key` that you copied in step 2 from [SearchApi](https://www.searchapi.io/) dashboard.
+6. [Optional] Enter the `SearchApi engine` name you want to query. Example, `google`, `bing`, `baidu`, `google_news`, `bing_news`, `google_videos`, `google_scholar` and `google_patents.` By default, it is set to `google`.
+7. Click `Save`.
+
+![Open WebUI Admin panel](../../static/img/tutorial_searchapi_search.png)
+
+#### Note
+You have to enable `Web search` in the prompt field, using plus (`+`) button to search the web using [SearchApi](https://www.searchapi.io/) engines.
+
+![enable Web search](../../static/img/enable_web_search.png)
+
 ## Google PSE API
 
 ### Setup