docs: use my own selling page

Author: amejiarosario

README.md

@@ -29,17 +29,17 @@ For a full list of all the exposed data structures and algorithms [see](https://
 
 ## Book
 
-You can check out the [dsa.js book](https://gum.co/dsajs) that goes deeper into each topic and provide additional illustrations and explanations.
+You can check out the [dsa.js book](https://books.adrianmejia.com) that goes deeper into each topic and provide additional illustrations and explanations.
 
 - Algorithmic toolbox to avoid getting stuck while coding.
 - Explains data structures similarities and differences.
 - Algorithm analysis fundamentals (Big O notation, Time/Space complexity) and examples.
 - Time/space complexity cheatsheet.
 
-<a href="https://gum.co/dsajs"><img src="https://user-images.githubusercontent.com/418605/55248546-60ebad80-5220-11e9-8cb5-85923f44e196.png" height="400px" alt="dsajs algorithms javascript book"></a>
+<a href="https://books.adrianmejia.com"><img src="https://user-images.githubusercontent.com/418605/55248546-60ebad80-5220-11e9-8cb5-85923f44e196.png" height="400px" alt="dsajs algorithms javascript book"></a>
 
 <!--
-WARNING: Although you can find the [book text on this repo](https://github.com/amejiarosario/dsa.js/blob/master/book/book.adoc), there are some things that doesn't work well with Github's Asciidoc unfortunately. For instance rendering Graphviz diagrams, internal link references, embedding code into docs and so on. For better reading experience and nicer presentation you can get the [PDF format here](https://gum.co/dsajs).
+WARNING: Although you can find the [book text on this repo](https://github.com/amejiarosario/dsa.js/blob/master/book/book.adoc), there are some things that doesn't work well with Github's Asciidoc unfortunately. For instance rendering Graphviz diagrams, internal link references, embedding code into docs and so on. For better reading experience and nicer presentation you can get the [PDF format here](https://books.adrianmejia.com).
 -->
 
 ## Data Structures

deprecated-README.adoc

@@ -18,7 +18,7 @@ toc::[]
 - Algorithm analysis fundamentals (Big O notation, Time/Space complexity) and examples.
 - Time/space complexity cheatsheet.
 
-image:book/cover.png[link=https://gum.co/dsajs, height=400]
+image:book/cover.png[link=https://books.adrianmejia.com, height=400]
 
 == Data Structures
 We are covering the following data structures.