docs: Improve Acyclic Visitor and Adapter readmes

acyclic-visitor/README.md

@@ -160,3 +160,5 @@ Trade-offs:
 
 * [Acyclic Visitor by Robert C. Martin](http://condor.depaul.edu/dmumaugh/OOT/Design-Principles/acv.pdf)
 * [Acyclic Visitor in WikiWikiWeb](https://wiki.c2.com/?AcyclicVisitor)
+* [Design Patterns: Elements of Reusable Object-Oriented Software](https://www.amazon.com/gp/product/0201633612/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0201633612&linkCode=as2&tag=javadesignpat-20&linkId=675d49790ce11db99d90bde47f1aeb59)
+* [Head First Design Patterns: A Brain-Friendly Guide](https://www.amazon.com/gp/product/0596007124/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596007124&linkCode=as2&tag=javadesignpat-20&linkId=6b8b6eea86021af6c8e3cd3fc382cb5b)

adapter/README.md

@@ -3,15 +3,18 @@ title: Adapter
 category: Structural
 language: en
 tag:
+  - Compatibility
   - Gang of Four
+  - Integration
 ---
 
 ## Also known as
+
 Wrapper
 
 ## Intent
-Convert the interface of a class into another interface the clients expect. Adapter lets classes work together that 
+
-couldn't otherwise because of incompatible interfaces.
+The Adapter pattern converts the interface of a class into another interface that clients expect, enabling compatibility.
 
 ## Explanation
 
@@ -92,9 +95,11 @@ captain.row();
 ```
 
 ## Class diagram
+
 ![alt text](./etc/adapter.urm.png "Adapter class diagram")
 
 ## Applicability
+
 Use the Adapter pattern when
 
 * You want to use an existing class, and its interface does not match the one you need
@@ -111,6 +116,7 @@ Use the Adapter pattern when
 
 
 ## Consequences
+
 Class and object adapters have different trade-offs. A class adapter
 
 *	Adapts Adaptee to Target by committing to a concrete Adaptee class. As a consequence, a class adapter won’t work when we want to adapt a class and all its subclasses.