Instruction description enhancement

**Is your feature request related to a problem? Please describe.**
On Instructions yaml files: `Excluded by` field can only take one extensions, but an instruction could be excluded by more that one extension.

**Describe the solution you'd like**
Set it has the `definedBy:` field. Let it have anyOf, allOf.

**Additional context**
Zext.h example:
  excludedBy: [Zk, Zkn, Zks, Zbkb] 
