dev-ml/*: improve metadata

Signed-off-by: Alessandro Barbieri <lssndrbarbieri@gmail.com>

dev-ml/mirage/metadata.xml

@@ -1,11 +1,31 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
 <pkgmetadata>
-   <maintainer type="person">
-        <email>lssndrbarbieri@gmail.com</email>
-        <name>Alessandro Barbieri</name>
-    </maintainer>
-   <upstream>
-        <remote-id type="github">mirage/mirage</remote-id>
-    </upstream>
+	<maintainer type="person">
+		<email>lssndrbarbieri@gmail.com</email>
+		<name>Alessandro Barbieri</name>
+	</maintainer>
+	<longdescription lang="en">MirageOS is a library operating system that constructs unikernels for
+secure, high-performance network applications across a variety of
+cloud computing and mobile platforms. Code can be developed on a
+normal OS such as Linux or MacOS X, and then compiled into a
+fully-standalone, specialised unikernel that runs under the Xen
+hypervisor.
+
+Since Xen powers most public cloud computing infrastructure such as
+Amazon EC2 or Rackspace, this lets your servers run more cheaply,
+securely and with finer control than with a full software stack.</longdescription>
+	<upstream>
+		<doc>https://mirage.github.io/mirage/</doc>
+		<bugs-to>https://github.com/mirage/mirage/issues/</bugs-to>
+		<remote-id type="github">mirage/mirage</remote-id>
+		<maintainer>
+			<name>Thomas Gazagnaire</name>
+			<email>thomas@gazagnaire.org</email>
+		</maintainer>
+		<maintainer>
+			<name>Anil Madhavapeddy</name>
+			<email>anil@recoil.org</email>
+		</maintainer>
+	</upstream>
 </pkgmetadata>