Document Config/Bioconductor/UnsupportedPlatforms (#165)

Co-authored-by: A Wokaty <awokaty@users.noreply.github.com>

Author: jwokaty

advanced-build-options.Rmd

@@ -11,6 +11,10 @@ platform--`win`, `win64`, or `mac`--or the name of a build node. For example
 
     UnsupportedPlatforms: win64, kjohnson3
 
+**Note**: Newer packages should use `Config/Bioconductor/UnsupportedPlatforms`
+as described in [the DESCRIPTION file][description-file] for the transition to
+R Universe.
+
 ## Optional builds: long tests and GPU builds
 
 Two optional builds are available to software packages: long tests and GPU

description-file.Rmd

@@ -221,3 +221,10 @@ during package installation.
 This is required if submitting a `Docker` or `Workflow`.
 Otherwise this field could optionally define the type of Bioconductor package
 `Software`, `ExperimentData`, `Annotation`.
+
+## `Config/Bioconductor/UnsupportedPlatforms` {#description-unsupportedplatforms}
+
+Add this field to exclude a package binary being propagated for unsupported
+platforms. Possible values are `windows`, `windows-x64`, `macosx`,
+`macosx-x86_64`, `macosx-arm64`. Multiple os-arch types should be separated by
+commas. The option `macosx` excludes the package from all macosx builds.