Adding Revision History section to pattern template

[spier]

Idea: how about we add a Revision History section, @spier , @lenucksi ? I feel it's kinda odd to have more than one entry in the Status section. Just my 0.02 $.

Originally posted by @gruetter in https://github.com/InnerSourceCommons/InnerSourcePatterns/pull/254#discussion_r554127296

[lenucksi]

Sounds good to me, we'll need that ( + changelog and addressability) for a regular release of the "book" or website anyway.

How do we go at it? A simple 0.x for 1-initials 2.x for 2-structured 3.x for our highest grade?

counted in the footer? Would be great to be able to parse around a bit.