fix markdown

Author: coke

solutions/rakudo/Configurable-REPL.md

@@ -26,7 +26,9 @@ Each which supports the following interpolations:
 
 The escape character allows us to generate ANSI colors, e.g.
 
-`RAKUDO_REPL_PROMPT='[\e[0;31m\i\e[0m] >'
+```
+RAKUDO_REPL_PROMPT='[\e[0;31m\i\e[0m] >
+```
 
 Would generate a prompt similar to the default except the index would appear in red.