dev-python/moderngl: update upstream metadata

Signed-off-by: Anna (cybertailor) Vyalkova <cyber+gentoo@sysrq.in>

dev-python/moderngl/metadata.xml

@@ -1,5 +1,5 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE pkgmetadata SYSTEM 'https://www.gentoo.org/dtd/metadata.dtd'>
+<?xml version='1.0' encoding='UTF-8'?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
 <pkgmetadata>
 	<maintainer type="person">
 		<email>gasc@eurecom.fr</email>
@@ -8,5 +8,7 @@
 	<upstream>
 		<remote-id type="pypi">moderngl</remote-id>
 		<remote-id type="github">moderngl/moderngl</remote-id>
+		<doc>https://moderngl.readthedocs.io/</doc>
+		<bugs-to>https://github.com/moderngl/moderngl/issues/</bugs-to>
 	</upstream>
 </pkgmetadata>