Added more Red Gate material

Added the latest Red Gate SQL book, as well as a link to the complete Red Gate "library".

free-programming-books.md

@@ -182,6 +182,7 @@
 * [Theassayer.org](http://theassayer.org/)
 * [tutorialspoint](http://www.tutorialspoint.com/)
 * [Wikibooks: Programming](http://en.wikibooks.org/wiki/Category%3aComputer_programming)
+* [Red Gate Books](http://www.red-gate.com/community/books/index)
 
 
 ###Graphics Programming
@@ -1593,6 +1594,7 @@ See also [TeX](#tex)
 * [How to Become an Exceptional DBA](http://www.red-gate.com/community/books/exceptional-dba-book) *(RedGate, By Brad McGehee)*
 * [SQL Server Stumpers Vol.5](http://www.red-gate.com/community/books/sql-server-stumpers-v5.htm) *(RedGate, By SQLServerCentral Authors)*
 * [Mastering SQL Server Profiler](http://www.red-gate.com/community/books/mastering-sql-server-profiler.htm) *(RedGate, By Brad McGehee)*
+* [Tribal SQL](http://www.red-gate.com/community/books/tribal-sql) *(RedGate & MidnightDBA, by various new SQL Server authors)*
 
 
 ###Standard ML