CubicSDR: add comments about wx and OSX requirements

science/CubicSDR/Portfile

@@ -25,6 +25,9 @@ checksums           rmd160 9e54b818c5777fefce428995e99f8ee60a7249f7 \
                     size   36027266
 revision            2
 
+# CubicSDR requires wxWidgets.use of wxWidgets-3.1 or newer -- "3.2"
+# by the wxWidgets PG -- which is what this provides. selecting 3.0
+# does not work.
 wxWidgets.use       wxWidgets-3.2
 
 depends_lib-append \
@@ -67,6 +70,9 @@ default_variants-append +bundle
 # set internal to the build.
 patchfiles-append patch-fix-build-older-osx.diff
 
+# CubicSDR requires wxWidgets.use of wxWidgets-3.1 or newer -- "3.2"
+# by the wxWidgets PG -- and the wxWidgets 3.2 options do not build on
+# older than OSX 10.7, so this is a solid requirement.
 if {${os.platform} eq "darwin" && ${os.major} < 11} {
     pre-fetch {
         ui_error "${subport} @${version} requires OS X 10.7 or newer"