added octave cheatsheet (#8279)

* added octave cheatsheet

* lineSpacing changes

* done the suggested changes

Co-authored-by: VaibhavDubeySSE <vaibhav.dubey@lntinfotech.com>

more/free-programming-cheatsheets.md

@@ -29,6 +29,7 @@
 * [Markdown](#markdown)
 * [MATLAB](#matlab)
 * [MongoDB](#mongodb)
+* [Octave](#octave)
 * [Perl](#perl)
 * [PHP](#php)
 * [Python](#python)
@@ -288,6 +289,11 @@
 * [Quick Cheat Sheet for Mongo DB Shell commands](https://gist.github.com/michaeltreat/d3bdc989b54cff969df86484e091fd0c) - Michael Treat's Quick Cheat Sheet (GitHub Gist)
 
 
+### Octave
+
+* [Octave Cheat Sheet](https://www.lehman.edu/academics/cmacs/documents/refcard-a4.pdf) - John W. Eaton (PDF)
+
+
 ### Perl
 
 * [Perl Cheat Sheet](https://www.pcwdld.com/perl-cheat-sheet) - Hitesh J (HTML)