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>

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)