chore: update cloud rad doclet (#329)

Author: eaball35

api-common-java/build.gradle

@@ -353,7 +353,7 @@ task javadocCombinedV3(type: Javadoc) {
   options.addStringOption('encoding', 'UTF-8')
   options.addStringOption("doclet", "com.microsoft.doclet.DocFxDoclet")
   options.addStringOption("projectname", "api-common")
-  options.docletpath = [file(System.getenv('KOKORO_GFILE_DIR') + "/java-docfx-doclet-1.4.0.jar")]
+  options.docletpath = [file(System.getenv('KOKORO_GFILE_DIR') + "/java-docfx-doclet-1.5.0.jar")]
   // Newer Gradle 6 passes -notimestamp by default, which the doclet above doesn't understand:
   // https://github.com/gradle/gradle/issues/11898
   options.noTimestamp false