Rearrange handbook handbook table of contents

@sytses, we have an action item to

Move general under people operations

After discussing it with @BarbieGitLab, it seems there are at least a handful of items that don't feel like they belong under People Ops' header section in the list, so I've attempted instead to move as much of the General section to other sections of the table.

I left a much smaller General section at that top, which includes our Values because I want that link to appear first and foremost.