tour: adds additional info RE 'else' command

Fixes golang#442

content/flowcontrol.article

@@ -69,6 +69,8 @@ of the `else` blocks.
 (Both calls to `pow` are executed and return before the call to `fmt.Println`
 in `main` begins.)
 
+*Note:* Unlike many other languages, Go insists that the `else` must be placed on the same line as the closing brace from the connected `if` statement.
+
 .play flowcontrol/if-and-else.go
 
 * Exercise: Loops and Functions