minor documentation improvement [ci skip]

activesupport/lib/active_support/core_ext/string/strip.rb

@@ -17,8 +17,8 @@ class String
   #
   # the user would see the usage message aligned against the left margin.
   #
-  # Technically, it looks for the least indented line in the whole string, and removes
-  # that amount of leading whitespace.
+  # Technically, it looks for the least indented non-empty line
+  # in the whole string, and removes that amount of leading whitespace.
   def strip_heredoc
     indent = scan(/^[ \t]*(?=\S)/).min.try(:size) || 0
     gsub(/^[ \t]{#{indent}}/, '')