Added Resources for Blockchain And Solidity (HacktoberFest) (#5973)

* Added free-programming-playgrounds for Solidity

* Added free-programming-interactive-tutorials-en for Solidity

* Update free-programming-interactive-tutorials-en.md

* Added free-programming-cheatsheets for Solidity

* Added free-courses-en for Blockchain

* Update free-courses-en.md

* Update free-courses-en.md

* Update free-courses-en.md

* Update free-programming-cheatsheets.md

* Update free-programming-cheatsheets.md

* Update free-programming-cheatsheets.md

* Update free-courses-en.md

* Update free-programming-playgrounds.md

* Update free-programming-cheatsheets.md

* Update free-programming-interactive-tutorials-en.md

* Update free-programming-playgrounds.md

* Recover deleted Manoj Ramesh resource

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

* Update more/free-programming-playgrounds.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

* add creator

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

Co-authored-by: Eric Hellman <eric@hellman.net>
Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

courses/free-courses-en.md

@@ -64,6 +64,7 @@
 * [Rust](#rust)
 * [Scala](#scala)
 * [Security](#security)
+* [Solidity](#solidity)
 * [Swift](#swift)
   * [Vapor](#vapor)
 * [Theory](#theory)
@@ -810,6 +811,12 @@
 * [Zero to Hero: A Practical Network Penetration Testing Course](https://www.youtube.com/playlist?list=PLLKT__MCUeiwBa7d7F_vN1GUwz_2TmVQj) - The Cyber Mentor
 
 
+### Solidity
+
+* [Learn Solidity](https://youtube.com/playlist?list=PL16WqdAj66SCOdL6XIFbke-XQg2GW_Avg) - Will it Scale (Youtube)
+* [MASTER Solidity for Blockchain](https://youtube.com/playlist?list=PLS5SEs8ZftgVnWHv2_mkvJjn5HBOkde3g) - Dapp University (Youtube)
+
+
 ### Swift
 
 * [100 days of Swift](https://www.hackingwithswift.com/100) - Hacking With Swift

more/free-programming-cheatsheets.md

@@ -27,6 +27,7 @@
 * [R](#r)
 * [Ruby](#ruby)
 * [Rust](#rust)
+* [Solidity](#solidity)
 * [SQL](#sql)
 
 
@@ -197,6 +198,12 @@
 * [Rust Language Cheat Sheet](https://cheats.rs) (HTML)
 
 
+### Solidity
+
+* [Solidity Cheat Sheet](https://intellipaat.com/mediaFiles/2019/03/Solidity-Cheat-Sheet.pdf) - IntelliPaat (PDF)
+* [Solidity Cheatsheet and Best practices](https://manojpramesh.github.io/solidity-cheatsheet/) - Manoj Ramesh
+
+
 ### SQL
 
 * [MySQL Cheatsheet](https://s3-us-west-2.amazonaws.com/dbshostedfiles/dbs/sql_cheat_sheet_mysql.pdf) - Database Star (PDF)

more/free-programming-interactive-tutorials-en.md

@@ -41,6 +41,7 @@
 * [Rust](#rust)
 * [Scala](#scala)
 * [Selenium](#selenium)
+* [Solidity](#solidity)
 * [SQL](#sql)
 * [Vim](#vim)
 
@@ -339,6 +340,11 @@
 * [Selenium Tutorial - Web Automation](http://www.techbeamers.com/selenium-webdriver-tutorial)
 
 
+### Solidity
+
+* [CryptoZombies.io](https://cryptozombies.io) - Loom Network
+
+
 ### SQL
 
 * [Intro to SQL: Querying and managing data](https://www.khanacademy.org/computing/computer-programming/sql) - Khan Academy

more/free-programming-playgrounds.md

@@ -250,7 +250,8 @@
 
 ### Solidity
 
-* [Remix IDE](https://remix.ethereum.org)
+* [ETH.Build](https://eth.build) - Austin Thomas Griffith
+* [Remix IDE](https://remix.ethereum.org) - ethereum.org
 
 
 ### SQL