readme: add missing backtick

README.md

@@ -212,7 +212,7 @@ included on the map.
 It currently does not read the tracker information directly.  However,
 if you click on the left/red "Copy killed NMs" button in the tracker to
 copy the list of currently dead NMs, you can paste it in game, e.g.
-`/echo ★ NMs on cooldown: Serket (7m) > Julika (24m) > Poly (54m)
+`/echo ★ NMs on cooldown: Serket (7m) > Julika (24m) > Poly (54m)`
 
 If you do not see the emoji, make sure you have installed [this Windows update](https://support.microsoft.com/en-us/help/2729094/an-update-for-the-segoe-ui-symbol-font-in-windows-7-and-in-windows-ser).