dev-cpp/valijson: add comment wrt test restriction

It was added in 44f039de30.

Signed-off-by: Sam James <sam@gentoo.org>

dev-cpp/valijson/valijson-1.0.5.ebuild

@@ -12,6 +12,9 @@ SRC_URI="https://github.com/tristanpenman/valijson/archive/v${PV}.tar.gz -> ${P}
 LICENSE="BSD-2 Boost-1.0"
 SLOT="0"
 KEYWORDS="~amd64 ~arm64 ~x86"
+# Bundled test dependencies are included as submodules, so not in github
+# autogenerated tarballs. The dependencies are largely packaged, but
+# needs patching to use those.
 RESTRICT="test"
 
 src_install() {