docs: Use # to reference instance methods (#270)

Fixes #269

We should use `XXX#method` not `XXX.method` to reference instance methods.

Author: pboling

lib/rexml/cdata.rb

@@ -58,7 +58,7 @@ def value
     #  c = CData.new( " Some text " )
     #  c.write( $stdout )     #->  <![CDATA[ Some text ]]>
     def write( output=$stdout, indent=-1, transitive=false, ie_hack=false )
-      Kernel.warn( "#{self.class.name}.write is deprecated", uplevel: 1)
+      Kernel.warn( "#{self.class.name}#write is deprecated", uplevel: 1)
       indent( output, indent )
       output << START
       output << @string

lib/rexml/comment.rb

@@ -48,7 +48,7 @@ def clone
     # ie_hack::
     #    Needed for conformity to the child API, but not used by this class.
     def write( output, indent=-1, transitive=false, ie_hack=false )
-      Kernel.warn("Comment.write is deprecated.  See REXML::Formatters", uplevel: 1)
+      Kernel.warn("#{self.class.name}#write is deprecated.  See REXML::Formatters", uplevel: 1)
       indent( output, indent )
       output << START
       output << @string

lib/rexml/element.rb

@@ -1496,7 +1496,7 @@ def texts
     #  doc.write( out )     #-> doc is written to the string 'out'
     #  doc.write( $stdout ) #-> doc written to the console
     def write(output=$stdout, indent=-1, transitive=false, ie_hack=false)
-      Kernel.warn("#{self.class.name}.write is deprecated.  See REXML::Formatters", uplevel: 1)
+      Kernel.warn("#{self.class.name}#write is deprecated.  See REXML::Formatters", uplevel: 1)
       formatter = if indent > -1
           if transitive
             require_relative "formatters/transitive"

lib/rexml/instruction.rb

@@ -49,7 +49,7 @@ def clone
     # See the rexml/formatters package
     #
     def write writer, indent=-1, transitive=false, ie_hack=false
-      Kernel.warn( "#{self.class.name}.write is deprecated", uplevel: 1)
+      Kernel.warn( "#{self.class.name}#write is deprecated", uplevel: 1)
       indent(writer, indent)
       writer << START
       writer << @target

lib/rexml/node.rb

@@ -26,7 +26,7 @@ def previous_sibling_node
     #   REXML::Formatters package for changing the output style.
     def to_s indent=nil
       unless indent.nil?
-        Kernel.warn( "#{self.class.name}.to_s(indent) parameter is deprecated", uplevel: 1)
+        Kernel.warn( "#{self.class.name}#to_s(indent) parameter is deprecated", uplevel: 1)
         f = REXML::Formatters::Pretty.new( indent )
         f.write( self, rv = "" )
       else

lib/rexml/text.rb

@@ -287,7 +287,7 @@ def indent_text(string, level=1, style="\t", indentfirstline=true)
     # See REXML::Formatters
     #
     def write( writer, indent=-1, transitive=false, ie_hack=false )
-      Kernel.warn("#{self.class.name}.write is deprecated.  See REXML::Formatters", uplevel: 1)
+      Kernel.warn("#{self.class.name}#write is deprecated.  See REXML::Formatters", uplevel: 1)
       formatter = if indent > -1
           REXML::Formatters::Pretty.new( indent )
         else