Update plugin files

project/plugin-eclipse.sbt

@@ -1,2 +1,2 @@
+// Plugin for generating Eclipse project configuration
 addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "5.2.2")
-

project/plugin-pgp.sbt

@@ -1,2 +1,2 @@
+// Plugin for doing PGP signatures for releases
 addSbtPlugin("com.jsuereth" % "sbt-pgp" % "1.1.0")
-

project/plugin-release.sbt

@@ -1,2 +1,2 @@
+// Plugin that automates the standard release process
 addSbtPlugin("com.github.gseitz" % "sbt-release" % "1.0.6")
-

project/plugin-site.sbt

@@ -1,2 +1,2 @@
+// Standard plugin for generating docs, etc.
 addSbtPlugin("com.typesafe.sbt" % "sbt-site" % "1.3.1")
-

project/plugin-sonatype.sbt

@@ -1,2 +1,4 @@
+/* Plugin that provides connectivity to the Sonatype repo, where many open
+ * source projects are hosted. (Projects published here are automatically
+ * synchronized to Maven central.) */
 addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "2.0")
-