powerpc: Document the existance of powerpc
@@ -2170,7 +2170,7 @@ arbitrarily complex configurations through nesting.
The following configurations must be defined by the implementation:
* `target_arch = "..."`. Target CPU architecture, such as `"x86"`, `"x86_64"`
- `"mips"`, `"arm"`, or `"aarch64"`.
+ `"mips"`, `"powerpc"`, `"arm"`, or `"aarch64"`.
* `target_endian = "..."`. Endianness of the target CPU, either `"little"` or
`"big"`.
* `target_family = "..."`. Operating system family of the target, e. g.
