Add documentation for file search workflow in omnibox/chat

Author: jdorfman

docs/omnibox/query-types/file-search.mdx

@@ -1 +1,21 @@
 # File Search
+
+<p className="subtitle">File Search is a query type or workflow that enables users to locate specific files across repositories and perform targeted analysis on the selected files through natural language follow-up queries.</p>
+
+File Search simplifies the process of finding and analyzing specific file types across your codebase. Unlike traditional code search, this workflow allows you to first identify relevant files (for example, all `package.json` files), select the specific files you want to analyze, and then ask follow-up questions about the selected files.
+
+This two-step approach is particularly powerful when you need to analyze patterns or extract information from similar files spread across multiple repositories. For instance, you could identify all configuration files, select the ones from relevant services, and then analyze their contents for inconsistencies or gather specific information through natural language queries.
+
+### Try it
+
+1. Type `package.json`
+2. Above the results, you will find the message "Query review selected a code search response."
+3. Follow up with `List all the dependencies used across these package.json files`
+
+### Demo
+
+🔴 Draft, replace with final version and upload to GCP 🔴 
+
+<video width="100%" controls>
+  <source src="https://p21.p4.n0.cdn.zight.com/items/BlumxXBE/55c5afa3-dee3-4b6c-bfd9-d3802360db2f.mp4?v=ec57e9a8c8e4a3d3af88635fcaf796d7" type="video/mp4" />
+</video>