add rerun function from within the listing-float

doc/test-samurai.txt

@@ -57,6 +57,7 @@ Additional keymaps:
   <leader>sf    Filter listing to [ FAIL ] only
   <leader>ss    Filter listing to [ SKIP ] only
   <leader>sa    Show all listing entries (clear filter)
+  <leader>tt    Run the test under the cursor in the listing
   <leader>o     Jump to test location
   <leader>z     Toggle Detail-Float full width
   <C-l>         Focus Detail-Float (press l again for full)