Added three books by Prakash B Hegade (#3968)

* Added three books by Prakash B Hegade

* Resubmitting PR with requested changes

free-programming-books.md

@@ -836,6 +836,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Building Blocks for Theoretical Computer Science](http://mfleck.cs.illinois.edu/building-blocks/index.html) - Margaret M. Fleck
 * [Category Theory for Computing Science](http://www.tac.mta.ca/tac/reprints/articles/22/tr22.pdf) (PDF)
 * [Category Theory for Programmers](https://github.com/hmemcpy/milewski-ctfp-pdf) - Bartosz Milewski (PDF)
+* [Design of a Programmer](https://www.smashwords.com/books/view/639609) - Prakash Hegade (PDF)
 * [Homotopy Type Theory: Univalent Foundations of Mathematics](http://homotopytypetheory.org/book/) (PDF)
 * [Introduction to Computer Science](http://www.cse.iitd.ernet.in/~suban/CSL102/) - Prof. Subhashis Banerjee, IIT Delhi
 * [Introduction to Computing](http://www.computingbook.org)
@@ -1023,11 +1024,13 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Essential C](http://cslibrary.stanford.edu/101/EssentialC.pdf) (PDF)
 * [Everything you need to know about pointers in C - Peter Hosey](http://boredzo.org/pointers/)
 * [Functional C (1997)](https://research.utwente.nl/files/5128727/book.pdf) - Pieter H. Hartel, Henk Muller (PDF)
+* [Hashing](https://www.smashwords.com/books/view/737188) - Prakash Hegade
 * [Learn to Code With C - The MagPi Essentials](https://www.raspberrypi.org/magpi-issues/Essentials_C_v1.pdf) (PDF)
 * [Modeling with Data](https://ben.klemens.org/pdfs/gsl_stats.pdf) - Ben Klemens (PDF)
 * [Modern C](https://modernc.gforge.inria.fr) - Jens Gustedt (PDF)
 * [Object-Oriented Programming With ANSI-C](http://www.planetpdf.com/codecuts/pdfs/ooc.pdf) (PDF)
 * [Programming in C](http://ee.hawaii.edu/~tep/EE160/Book/PDF/) - Bharat Kinariwala & Tep Dobry
+* [Structures and C](https://www.smashwords.com/books/view/644937) - Prakash Hegade
 * [The C book](http://publications.gbdirect.co.uk/c_book/)
 * [The Craft of Text Editing or A Cookbook for an Emacs](http://www.finseth.com/craft/) - Craig A. Finseth
 * [The Current C Programming Language Standard – ISO/IEC 9899:202x (C2x)](http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2310.pdf) - Open Standards Org - www.open-std.org (PDF)