Update README.md grammar (#11009)

Improve small mistakes :))

README.md

@@ -24,7 +24,7 @@ This page is available as an easy-to-read website. Access it by clicking on [![h
 
 This list was originally a clone of [StackOverflow - List of Freely Available Programming Books](https://web.archive.org/web/20140606191453/http://stackoverflow.com/questions/194812/list-of-freely-available-programming-books/392926) with contributions from Karan Bhangui and George Stocker.
 
-The list was moved to GitHub by Victor Felder for collaborative updating and maintenance. It has grown to become one of [GitHub's most popular repository](https://octoverse.github.com/).
+The list was moved to GitHub by Victor Felder for collaborative updating and maintenance. It has grown to become one of [GitHub's most popular repositories](https://octoverse.github.com/).
 
 <div align="center" markdown="1">
 
@@ -57,7 +57,7 @@ Click on these badges to see how you might be able to help:
 
 </div>
 
-## How to Share
+## How To Share
 
 <div align="left" markdown="1">
 <a href="https://www.facebook.com/share.php?u=https%3A%2F%2Fgithub.com%2FEbookFoundation%2Ffree-programming-books&p[images][0]=&p[title]=Free%20Programming%20Books&p[summary]=">Share on Facebook</a><br>
@@ -210,7 +210,7 @@ Free Podcasts and Screencasts:
 
 ### Programming Playgrounds
 
-Write, compile and run your code within a browser. Try it out!
+Write, compile, and run your code within a browser. Try it out!
 
 + [Chinese / 中文](more/free-programming-playgrounds-zh.md)
 + [English](more/free-programming-playgrounds.md)