Add break statement to cheatsheet.md

Added information about the existence of the break statement to the loop section.

cheatsheet.md

@@ -313,6 +313,15 @@ while (some_condition()) { /* do something */ }
 for (x : [1,2,3]) { print(i); }
 ```
 
+Each of the loop styles can be broken using the `break` statement. For example:
+
+```
+while (some_condition()) {
+  /* do something */
+  if (another_condition()) { break; }
+}
+```
+
 ## Conditionals
 
 ```