Added Solidity programming language and book (EbookFoundation#2373)

* added Solidity

* added Solidity

* added Solidity

* bitcoin book added

* fixed ordering on bitcoin book entry

* added authors for bitcoin and solidity books

free-programming-books.md

@@ -171,6 +171,7 @@
 * [Sed](#sed)
 * [Self](#self)
 * [Smalltalk](#smalltalk)
+* [Solidity](#solidity)
 * [Spark](#spark)
 * [SQL (implementation agnostic)](#sql-implementation-agnostic)
 * [SQL Server](#sql-server)
@@ -488,6 +489,7 @@
 * [Learning Docker](https://www.packtpub.com/packt/free-ebook/learning-docker) - Pethuru Raj, Jeeva S. Chelladhurai & Vinod Singh, Packt. (Just fill the fields with any values) 
 * [Linked Data Patterns: A pattern catalogue for modelling, publishing, and consuming Linked Data](http://patterns.dataincubator.org/book/) - Leigh Dodds, Ian Davis
 * [Magic Ink: Information Software and The Graphical Interface](http://worrydream.com/#!/MagicInk) - Bret Victor
+* [Mastering Bitcoin - Unlocking digital currencies](https://github.com/bitcoinbook/bitcoinbook) - Andreas M. Antonopoulos
 * [Mobile Developer's Guide to the Galaxy](https://leanpub.com/mobiledevelopersguide)
 * [Modeling Reactive Systems with Statecharts](http://www.wisdom.weizmann.ac.il/~harel/reactive_systems.html)
 * [Mother Tongues of Computer Languages](http://www.digibarn.com/collections/posters/tongues/) (PNG)
@@ -2151,6 +2153,11 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Stef's Free Online Smalltalk Books](http://stephane.ducasse.free.fr/FreeBooks.html) (meta-list)
 
 
+### Solidity
+
+* [A 101 Noob Intro to Programming Smart Contracts on Ethereum](https://consensys.github.io/developers/articles/101-noob-intro/) - Eva Shon
+
+
 ### Spark
 
 * [Databricks Spark Knowledge Base](https://www.gitbook.com/book/databricks/databricks-spark-knowledge-base/details)