Created readme file with some basic RTF documentation.
 On branch rtf_documentation
new file:   README.md
Added reference to Perl module.
Added download links to RTF specification.
Guiding principles updated.
On branch rtf_documentation
modified:   README.md
Basic RTF syntax.
Sample RTF file added.
Made the four RTF categories into a list.
Corrected typo; code formatting for curly brackets.
Added missing empty line before numbered list.
Added numbers to sub-headings.