README: fix location of tldr.zip (#268)

The script itself is already using GitHub releases,
but the readme hasn't been updated.

Author: acuteenvy

README.md

@@ -85,7 +85,7 @@ export TLDR_LANGUAGE="es"
 export TLDR_CACHE_ENABLED=1
 export TLDR_CACHE_MAX_AGE=720
 export TLDR_PAGES_SOURCE_LOCATION="https://raw.githubusercontent.com/tldr-pages/tldr/main/pages"
-export TLDR_DOWNLOAD_CACHE_LOCATION="https://tldr-pages.github.io/assets/tldr.zip"
+export TLDR_DOWNLOAD_CACHE_LOCATION="https://github.com/tldr-pages/tldr/releases/latest/download/tldr.zip"
 ```
 
 ### Cache