Add R cheatsheets (#5437)

* Add R section to cheetsheets

Add R Studio section to cheetsheets page

* Add link to RStudio official cheetsheets resources

Resources website: https://www.rstudio.com/resources/cheatsheets

* Add R cheetsheet: Data Wrangling with dplyr, tidyr

Data Wrangling with dplyr and tidyr cheetsheet (U.1/15) english
Public Url: https://www.rstudio.com/wp-content/uploads/2015/02/data-wrangling-cheatsheet.pdf

* Add R cheetsheet: Domar datos con dplyr y tidyr

Data Wrangling with dplyr and tidyr cheetsheet (U.1/15) spanish
Public Url: https://github.com/rstudio/cheatsheets/raw/master/translations/spanish/data-wrangling-cheatsheet_Spanish.pdf
Scrapped from: https://www.rstudio.com/resources/cheatsheets

* Add R cheetsheet: Domar datos con dplyr y tidyr

- Fix CI/CD errors.
- Data Wrangling with dplyr and tidyr cheetsheet (U.1/15) spanish
Public Url: https://github.com/rstudio/cheatsheets/raw/master/translations/spanish/data-wrangling-cheatsheet_Spanish.pdf
Scrapped from: https://www.rstudio.com/resources/cheatsheets

* Add R cheetsheet: Domar datos con dplyr y tidyr

- Fix CI/CD errors
- Data Wrangling with dplyr and tidyr cheetsheet (U.1/15) spanish
Public Url: https://github.com/rstudio/cheatsheets/raw/master/translations/spanish/data-wrangling-cheatsheet_Spanish.pdf
Scrapped from: https://www.rstudio.com/resources/cheatsheets

* Revert RStudio Data Wrangling cheatcheats (KISS)

- Keep It Simple / apply review suggestions. Thus, I remove "Data Wrangling" cheatsheets because it already are present in the RStudio portal that link points to.
- Fix grammar.

more/free-programming-cheatsheets.md

@@ -18,6 +18,7 @@
 * [MongoDB](#mongodb)
 * [Perl](#Perl)
 * [Python](#python)
+* [R](#R)
 * [Ruby](#ruby)
 * [SQL](#sql)
 
@@ -130,6 +131,11 @@
 * [Python WorldWide Cheatsheet](https://cheatography.com/davechild/cheat-sheets/python/) - Cheatography (Python)
 
 
+### R
+
+* [All RStudio cheatsheets resources](https://www.rstudio.com/resources/cheatsheets) - RStudio.com (HTML site with PDF links)
+
+
 ### Ruby
 
 * [Ruby Cheat Sheet](https://www.codeconquest.com/wp-content/uploads/Ruby-Cheat-Sheet-by-CodeConquestDOTcom.pdf) - CodeConquest.com (PDF)