dev-python/tweepy: update upstream metadata

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

dev-python/tweepy/metadata.xml

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="UTF-8"?>
+<?xml version='1.0' encoding='UTF-8'?>
 <!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
 <pkgmetadata>
 	<maintainer type="person">
@@ -7,5 +7,6 @@
 	</maintainer>
 	<upstream>
 		<remote-id type="github">tweepy/tweepy</remote-id>
+		<doc>https://tweepy.readthedocs.io</doc>
 	</upstream>
 </pkgmetadata>