feature-request: run a command IF a condition passes#312

just like **[LINK](https://github.com/anishathalye/dotbot#format)** directive, there should one for running individual commands for SHELL directive. Ex: ```yaml - shell: - command: apt update && apt upgrade -y if: lsb_release -i | grep -io 'debian' description: Update APT package repository - command: dnf update -y if: lsb_release -i | grep -io 'fedora' description: Update DNF package repository ``` ## why - provides a better flow of running dotbot process - can contain similar commands in a single shell directive. - Ex: shell directive for updating repositories - Ex: installing a package using package manager in one OS, downloading a script from another OS