Merge pull request #150 from yarikoptic/doc-mkdir-p

DOC: use -p with mkdir ~/bin since might exist already

Author: r2d4

README.md

@@ -28,7 +28,7 @@ curl -LO https://storage.googleapis.com/container-diff/latest/container-diff-lin
 OR, if you want to avoid using sudo:
 
 ```shell
-curl -LO https://storage.googleapis.com/container-diff/latest/container-diff-linux-amd64 && chmod +x container-diff-linux-amd64 && mkdir $HOME/bin && export PATH=$PATH:$HOME/bin && mv container-diff-linux-amd64 $HOME/bin/container-diff
+curl -LO https://storage.googleapis.com/container-diff/latest/container-diff-linux-amd64 && chmod +x container-diff-linux-amd64 && mkdir -p $HOME/bin && export PATH=$PATH:$HOME/bin && mv container-diff-linux-amd64 $HOME/bin/container-diff
 ```
 
 ### Windows