main/cmake: add comment on jsoncpp

main/cmake/APKBUILD

@@ -42,6 +42,8 @@ prepare() {
 
 build() {
 	cd "$_builddir"
+	# jsoncpp seems to need cmake to build so to avoid recursive build dep
+	# we use the bundled
 	./bootstrap --prefix=/usr \
 		--mandir=/share/man \
 		--datadir=/share/$pkgname \