fix(route): complete GitHub file params (#14987)

* fix(route): complete GitHub file params

* Apply suggestions from code review

Co-authored-by: Tony <TonyRL@users.noreply.github.com>

--------

lib/routes/github/file.ts

@@ -5,14 +5,21 @@ import queryString from 'query-string';
 
 export const route: Route = {
     path: '/file/:user/:repo/:branch/:filepath{.+}',
+    example: '/github/file/DIYgod/RSSHub/master/README.md',
+    parameters: {
+        user: "GitHub user or org name",
+        repo: "repository name",
+        branch: "branch name",
+        filepath: "path of target file",
+    },
     radar: [
         {
             source: ['github.com/:user/:repo/blob/:branch/*filepath'],
             target: '/file/:user/:repo/:branch/:filepath',
         },
     ],
-    name: 'Unknown',
-    maintainers: [],
+    name: 'File Commits',
+    maintainers: ['zengxs'],
     handler,
 };