Update Validation page

[TinaKT]

Update the validation page with answers to the following questions:

• A validator needs to stake a part of its CCD balance on the validator account. - is there a percentage or formula how much validator needs to stake?
• Later, the validator can then manually release a part of or all of the staked amount. - can we be a bit more specific, when exactly is “later”?
• To be chosen to produce a block, the validator must take part in a lottery. - is there a documentation about lottery that we can refer people to?
• Validators sign a block when they have verified that it is valid - how exactly do validators validate a block? Any link we can refer readers to?