Merge pull request #1944 from ngetchell/master

Updated the PowerShell.org free ebooks. 

free-programming-books.md

@@ -1658,17 +1658,21 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 
 ### PowerShell
 
-* [Creating HTML Reports in PowerShell](https://www.penflip.com/powershellorg/creating-html-reports-in-powershell) (PDF,ePub,HTML)
-* [Introduction to PowerShell for Unix People](https://www.penflip.com/powershellorg/a-unix-persons-guide-to-powershell) (PDF, ePub, HTML)
+* [Creating HTML Reports in PowerShell](https://www.gitbook.com/book/devopscollective/creating-html-reports-in-powershell/details) (PDF,ePub,HTML)
+* [DevOps: The Ops Perspective](https://www.gitbook.com/book/devopscollective/devops-the-ops-perspective/details) (PDF, ePub, MOBI)
+* [Ditch Excel: Making Historical & Trend Reports in PowerShell](https://www.gitbook.com/book/devopscollective/ditch-excel-making-historical-trend-reports-in-po/details)(PDF, ePub, MOBI)
+* [Introduction to PowerShell for Unix People](https://www.gitbook.com/book/devopscollective/a-unix-person-s-guide-to-powershell/details) (PDF, ePub, HTML)
 * [Layman’s Guide to PowerShell 2.0 remoting](http://www.ravichaganti.com//blog/wp-content/uploads/2010/12/A%20layman's%20guide%20to%20PowerShell%202.0%20remoting-v2.pdf) (PDF)
 * [Mastering PowerShell](http://powershell.com/cs/login.aspx?ReturnUrl=%2fcs%2fblogs%2febook%2fdefault.aspx)
 * [PowerShell 2.0 – One CMDLET At A Time](http://www.jonathanmedd.net/wp-content/uploads/2010/09/PowerShell_2_One_Cmdlet_at_a_Time.pdf) (PDF)
 * [PowerShell Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/powershell) (PDF, Kindle) *(Just fill the fields with any values)*
-* [The Big Book of PowerShell Error Handling](https://www.penflip.com/powershellorg/the-big-book-of-powershell-error-handling) (PDF, ePub, HTML)
-* [The Big Book of PowerShell Gotchas](https://www.penflip.com/powershellorg/the-big-book-of-powershell-gotchas) (PDF, ePub, HTML)
-* [The Community Book of PowerShell Best Practices](https://www.penflip.com/powershellorg/the-community-book-of-powershell-practices) (PDF, ePub, HTML)
+* [Secrets of PowerShell Remoting](https://www.gitbook.com/book/devopscollective/secrets-of-powershell-remoting/details) (PDF, ePub, MOBI)
+* [The Big Book of PowerShell Error Handling](https://www.gitbook.com/book/devopscollective/the-big-book-of-powershell-error-handling/details) (PDF, ePub, MOBI)
+* [The Big Book of PowerShell Gotchas](https://www.gitbook.com/book/devopscollective/the-big-book-of-powershell-gotchas/details) (PDF, ePub, MOBI)
 * [The DSC Book](https://www.penflip.com/powershellorg/the-dsc-book) (PDF, ePub, HTML)
-* [The Monad Manifesto - Annotated](https://www.penflip.com/powershellorg/monad-manifesto-annotated) (PDF, ePub, HTML)
+* [The Monad Manifesto - Annotated](https://www.gitbook.com/book/devopscollective/the-monad-manifesto-annotated/details) (PDF, ePub, MOBI)
+* [Why PowerShell?](https://www.gitbook.com/book/devopscollective/why-powershell-/details) (PDF, ePub, MOBI)
+* [Windows PowerShell Networking Guide](https://www.gitbook.com/book/devopscollective/windows-powershell-networking-guide/details) (PDF, ePub, MOBI)
 
 
 ### Processing