add newline after Usage:

Author: stmuk

doc/Type/Str.pod

@@ -25,6 +25,7 @@ Defined as:
     multi method chomp(Str:D:) returns Str:D
 
 Usage:
+
     chomp($string);
     $string.chomp;
 
@@ -45,6 +46,7 @@ Defined as:
     multi method lc(Str:D:) returns Str:D
 
 Usage:
+
     lc($string);
     $string.lc;