Change scaladoc link title to "API Documentation" (#2303)

* update sbt-microsites plugin

* add micrositeDocumentationLabelDescription on the docSettings

build.sbt

@@ -160,6 +160,7 @@ lazy val docSettings = Seq(
   micrositeHomepage := "http://typelevel.org/cats/",
   micrositeBaseUrl := "cats",
   micrositeDocumentationUrl := "/cats/api/cats/index.html",
+  micrositeDocumentationLabelDescription := "API Documentation",
   micrositeGithubOwner := "typelevel",
   micrositeExtraMdFiles := Map(
     file("CONTRIBUTING.md") -> ExtraMdFileConfig(

project/plugins.sbt

@@ -10,7 +10,7 @@ addSbtPlugin("com.typesafe.sbt"    % "sbt-git"               % "0.9.3")
 addSbtPlugin("org.scala-js"        % "sbt-scalajs"           % "0.6.22")
 addSbtPlugin("com.github.tkawachi" % "sbt-doctest"           % "0.8.0")
 addSbtPlugin("org.xerial.sbt"      % "sbt-sonatype"          % "2.0")
-addSbtPlugin("com.47deg"           % "sbt-microsites"        % "0.7.17")
+addSbtPlugin("com.47deg"           % "sbt-microsites"        % "0.7.20")
 addSbtPlugin("com.dwijnand"        % "sbt-travisci"          % "1.1.1")
 addSbtPlugin("org.lyranthe.sbt"    % "partial-unification"   % "1.1.1")
 addSbtPlugin("org.tpolecat"        % "tut-plugin"            % "0.6.4")