Reorg charter documentation

[ianbjacobs]

I've tried to simplify the explanations by:

1) Separating high-level process from implementation details 2) Separating "new" from "existing"

I've endeavored not to lose any requirements and also to take into account other edits that have happened this week re: Director-free.

[ianbjacobs]

Note: I did not spend much time on the "Implementation" section of the document other than to try to fold in @xueyuanjia edits.

[plehegar]

Some minor tweaks but looks great otherwise

[ianbjacobs]

@plh, I made changes based on your comments (mostly incorporating the suggestions).