Fix explanation of "and" and "or" in ruby.

ruby.html.markdown

@@ -79,10 +79,14 @@ true && false #=> false
 true || false #=> true
 !true #=> false
 
-# Alternate spellings of logical operators
-true and false #=> false
-true or false #=> true
-not true #=> false
+# There are alternate versions of the logical operators with much lower
+# precedence. These are meant to be used as flow-control constructs to chain
+# statements together until one of them returns true or false.
+
+# `do_something_else` only called if `do_something` succeeds.
+do_something() and do_something_else()
+# `log_error` only called if `do_something` fails.
+do_something() or log_error()
 
 
 # Strings are objects