docs: fix missing quotation marks in readme

Author: sijiaoh

README.md

@@ -273,7 +273,7 @@ Install the plugin with your preferred package manager:
       -- by default all keymaps are enabled, but you can disable some of them,
       -- by removing them from the list.
       -- If you rather use another key, you can map them
-      -- to something else, e.g., { [";"] = "L", [","] = H }
+      -- to something else, e.g., { [";"] = "L", [","] = "H" }
       keys = { "f", "F", "t", "T", ";", "," },
       ---@alias Flash.CharActions table<string, "next" | "prev" | "right" | "left">
       -- The direction for `prev` and `next` is determined by the motion.