static/frontend/homepage: fix symbols selector

Remove unnecessary "s" from query param.

For golang/go#44142

Change-Id: I7d843d650d915b364b1d581f7bc8d53928144b7c
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/343221
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
diff --git a/static/frontend/homepage/homepage.tmpl b/static/frontend/homepage/homepage.tmpl
index 8b30850..415974e 100644
--- a/static/frontend/homepage/homepage.tmpl
+++ b/static/frontend/homepage/homepage.tmpl
@@ -20,7 +20,7 @@
         {{if .Experiments.IsActive "symbol-search"}}
           <select name="m" class="go-Select">
             <option value="packages">Packages</option>
-            <option value="{{.SearchModeSymbol}}s">{{capitalize .SearchModeSymbol}}s</option>
+            <option value="{{.SearchModeSymbol}}">{{capitalize .SearchModeSymbol}}s</option>
           </select>
         {{end}}
         <input