Update README.md

[glensc]

update dependencies, used by scripts internally

[liske]

In case of Debian grep is essentials (priority required) and procps is priority important. I'm not going to add a essentials packet to the dependency list... (da|ba)sh would be required, too ;-)

[glensc]

well, in normal systems those are indeed present, but consider systems like docker where your system has only one purpose: run single process.