Fix non-root directory permission denied error (#578)

* Fix non-root directory permission denied error

* Updated Readme

* Fixed Readme

* Updated readme to use latest tag for QA error

* updated Dockerfile

* Moved error to others section

README.md

@@ -1955,6 +1955,19 @@ Try again with `--reset` option:
 ```
 $ trivy image --reset
 ```
+
+### Error: FATAL	unable to initialize the cache: failed to create cache dir: mkdir /root/.cache: permission denied
+
+```
+$ docker run --rm -v $PWD:/root/.cache/  aquasec/trivy:latest --cache-dir /root/.cache image centos:7
+2020-07-29T15:02:54.435Z	FATAL	unable to initialize the cache: failed to create cache dir: mkdir /root/.cache: permission denied
+```
+
+Try:
+
+```
+$ docker run --rm -v $PWD:/tmp/.cache/  aquasec/trivy:latest --cache-dir /tmp/.cache image centos:7
+```
 ---
 
 # Credits