where is the specification for bitcoin block-chain mining? 1.) Who wrote the rule book and where is it stored?  

2.) Is it stored in a block chain?  

3.) Who said bitcoin could hard-fork?  

4.) What if some bitcoin holders don't want a hard fork?
Who wrote the rule book


Satoshi, whoever that is, wrote the original set of rules. They have evolved a bit over time.


  and where is it stored?


In every node that runs bitcoin software.


  Is it stored in a block chain?


No.


  Who said bitcoin could hard-fork?


Nobody. It's a consequence of the way the system works. If two nodes use different rules, it's simply a fact that they can permanently disagree on which transactions are valid.


  What if some bitcoin holders don't want a hard fork


Then they should run code with the very same rule book as those who agree with them on what the rules should be. They will then never fork from each other, but the rest of the world may follow different rules. Nobody gets to force anyone else to use rules they don't wish to use, but only people who agree on rules can interact with each other.

This is why we have Bitcoin and Bitcoin Cash. There are two groups who cannot agree on the rules the system should follow.