update cache coder proverb

update the link that follow Phil Karlton proverb to point to martin fowler blog instead of google search

Author: abdoemr11

src/content/8/en/part8d.md

@@ -274,7 +274,7 @@ When necessary, it is possible to disable cache for the whole application or [si
 
 Be diligent with the cache. Old data in cache can cause hard-to-find bugs. As we know, keeping the cache up to date is very challenging. According to a coder proverb:
 
-> <i>There are only two hard things in Computer Science: cache invalidation and naming things.</i> Read more [here](https://www.google.com/search?q=two+hard+things+in+Computer+Science&oq=two+hard+things+in+Computer+Science).
+> <i>There are only two hard things in Computer Science: cache invalidation and naming things.</i> Read more [here](https://martinfowler.com/bliki/TwoHardThings.html).
 
 The current code of the application can be found on [Github](https://github.com/fullstack-hy2020/graphql-phonebook-frontend/tree/part8-8), branch <i>part8-8</i>.