Fix mill testing on mill 0.11 and add mill to README and comments (#119)

.github/workflows/template-cleanup.yml

@@ -30,7 +30,7 @@ jobs:
           GROUP="com.github.$SAFE_ORG"
 
           # Replace placeholders
-          sed -i "s/%NAME%/$NAME/g" build.sbt build.sc README.md
+          sed -i "s/%NAME%/$NAME/g" build.sbt build.sc README.md src/test/scala/gcd
           sed -i "s/%REPOSITORY%/${GITHUB_REPOSITORY/\//\\/}/g" README.md
           sed -i "s/%ORGANIZATION%/$GROUP/g" build.sbt
 

README.md

@@ -75,6 +75,11 @@ You can run the included test with:
 sbt test
 ```
 
+Alternatively, if you use Mill:
+```sh
+mill %NAME%.test
+```
+
 You should see a whole bunch of output that ends with something like the following lines
 ```
 [info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0

build.sc

@@ -23,7 +23,7 @@ object %NAME% extends SbtModule { m =>
   override def scalacPluginIvyDeps = Agg(
     ivy"org.chipsalliance:::chisel-plugin:5.0.0",
   )
-  object test extends Tests with ScalaTest {
+  object test extends SbtModuleTests with TestModule.ScalaTest {
     override def ivyDeps = m.ivyDeps() ++ Agg(
       ivy"edu.berkeley.cs::chiseltest:5.0.0"
     )

src/test/scala/gcd/GCDSpec.scala

@@ -11,11 +11,15 @@ import chisel3.experimental.BundleLiterals._
   * This is a trivial example of how to run this Specification
   * From within sbt use:
   * {{{
-  * testOnly gcd.GcdDecoupledTester
+  * testOnly gcd.GCDSpec
   * }}}
   * From a terminal shell use:
   * {{{
-  * sbt 'testOnly gcd.GcdDecoupledTester'
+  * sbt 'testOnly gcd.GCDSpec'
+  * }}}
+  * Testing from mill:
+  * {{{
+  * mill %NAME%.test.testOnly gcd.GCDSpec
   * }}}
   */
 class GCDSpec extends AnyFreeSpec with ChiselScalatestTester {