fix backticks

Author: fluentfuture

mug-guava/src/main/java/com/google/mu/safesql/README.md

@@ -110,7 +110,9 @@ compile-time-safe SQL templating system that addresses structure injection head-
 SafeSql query = SafeSql.of(
   "SELECT `{columns}` FROM users WHERE name LIKE '%{keyword}%'",
   /* columns */ List.of("id", "email"), /* keyword */ "100%");
-  
+```
+
+```java
 SafeSql query = SafeSql.of(
     "SELECT * FROM `{table}` WHERE status = {status}", table, status);
 ```