Possibly inaccurate document description

[hyLim6519]

Bug severity
3

Describe the bug
Not a bug on code but rather on documentation (markdown). It came to my notice that the documentation for mediation-manager markdown potentially have some flaw on the explanation on the coordinate mediation setup.

Observed behaviour

veramo/packages/mediation-manager/README.md

Lines 11 to 12 in e690f3c

	By default, the `isMediateGrantAll` policy is set to `true` meaning that any requests for mediation will be `GRANTED` unless their `did` is listed in the `preRequestPolicyStore` as `ALLOW`. Conversely, if the `isMediateGrantAll` policy is set to `false`, all requests will be allowed, unless they are listed in the `preRequestPolicyStore` as `ALLOW`.

Expected behaviour

By default, the `isMediateGrantAll` policy is set to `true` meaning that any requests for mediation will be `GRANTED` unless their `did` is listed in the `preRequestPolicyStore` as 
- `ALLOW` 
+ `DENY`.

Conversely, if the `isMediateGrantAll` policy is set to `false`, 
- all requests will be allowed, unless they are listed in the `preRequestPolicyStore` as `ALLOW`.
+ all requests for mediation will be `DENIED` , unless they are listed in the `preRequestPolicyStore` as `ALLOW`.

Additional context
The above is derived based on specification

[nickreynolds]

I'd agree with you here. Feel free to put up a PR to fix this, or I'll get to it when I have a chance