Minor tweak

Author: javiereguiluz

contributing/code/standards.rst

@@ -179,9 +179,9 @@ Structure
 
 * Exception and error message strings must be concatenated using :phpfunction:`sprintf`;
 
-* Exception and error messages must not contain backticks, even when referring to a
-  technical element (such as a method name for example). Double quotes must be used
-  at all time;
+* Exception and error messages must not contain backticks (e.g. 'The \`foo\` option ...'),
+  even when referring to a technical element (such as a method or variable name).
+  Double quotes must be used at all time (e.g. 'The "foo" option ...'),;
 
 * Exception and error messages must start with a capital letter and finish with a dot ``.``;