There was a new powerpc reference added recently (simple design and all)
For Anyone who hates official manual from the ibm website ..

Index:
https://fenixfox-studios.com/manual/powerpc/index.html
Registers:
https://fenixfox-studios.com/manual/powerpc/registers.html
Syntax:
https://fenixfox-studios.com/manual/powerpc/syntax.html

Instruction like:
add - https://fenixfox-studios.com/manual/powerpc/instructions/add.html
mflr - https://fenixfox-studios.com/manual/powerpc/instructions/mflr.html