Merge pull request #1942 from ncausey/patch-1

docs(caching): update docs for disabling cache expiration

Author: kamilmysliwiec

content/techniques/caching.md

@@ -58,10 +58,10 @@ You can manually specify a TTL (expiration time in seconds) for this specific ke
 await this.cacheManager.set('key', 'value', { ttl: 1000 });
 ```
 
-To disable expiration of the cache, set the `ttl` configuration property to `null`:
+To disable expiration of the cache, set the `ttl` configuration property to `0`:
 
 ```typescript
-await this.cacheManager.set('key', 'value', { ttl: null });
+await this.cacheManager.set('key', 'value', { ttl: 0 });
 ```
 
 To remove an item from the cache, use the `del` method: