Updated docs with information about `custom_target[i]`
## Can link against custom targets
-The output of `custom_target` can be used in `link_with` and
+The output of `custom_target` and `custom_target[i]` can be used in `link_with` and
`link_whole` keyword arguments. This is useful for integrating custom
code generator steps, but note that there are many limitations:
@@ -10,7 +10,8 @@ code generator steps, but note that there are many limitations:
- The user is responsible for ensuring that the code produced by
different toolchains are compatible.
- - The custom target can only have one output file.
+ - `custom_target` may only be used when it has a single output file.
+ Use `custom_target[i]` when dealing with multiple output files.
- The output file must have the correct file name extension.
