Remove references to BSD license; add NOTICE file

[dwickern]

Followup to #1661

[dwickern]

Looks like one of the builds hit sbt/sbt#7873

 [info] [launcher] getting org.scala-sbt sbt 2.0.0-M3  (this may take some time)...
 [info] [launcher] getting Scala 3.6.2 (for sbt)...
Error:  Exception in thread "sbt-parser-init-thread" java.lang.ExceptionInInitializerError
Error:  	at dotty.tools.dotc.core.Contexts$ContextBase.<init>(Contexts.scala:886)
Error:  	at dotty.tools.dotc.Driver.initCtx(Driver.scala:66)
Error:  	at sbt.internal.parser.SbtParser$ParseDriver.<init>(SbtParser.scala:141)
Error:  	at sbt.internal.parser.SbtParser$.$init$$$anonfun$1(SbtParser.scala:138)
Error:  	at sbt.internal.io.Retry$.apply(Retry.scala:47)
Error:  	at sbt.internal.io.Retry$.apply(Retry.scala:29)
Error:  	at sbt.internal.io.Retry$.apply(Retry.scala:24)
Error:  	at sbt.internal.parser.SbtParser$.<clinit>(SbtParser.scala:138)
Error:  	at sbt.internal.parser.SbtParserInit$$anon$1.run(SbtParser.scala:185)
Error:  Caused by: java.util.ConcurrentModificationException
Error:  	at java.util.Hashtable$Enumerator.next(Hashtable.java:1408)
Error:  	at scala.collection.convert.JavaCollectionWrappers$JPropertiesWrapper$$anon$6.next(JavaCollectionWrappers.scala:613)
Error:  	at scala.collection.convert.JavaCollectionWrappers$JPropertiesWrapper$$anon$6.next(JavaCollectionWrappers.scala:609)
Error:  	at scala.collection.IterableOnceOps.find(IterableOnce.scala:677)
Error:  	at scala.collection.IterableOnceOps.find$(IterableOnce.scala:674)
Error:  	at scala.collection.AbstractIterator.find(Iterator.scala:1303)
Error:  	at dotty.tools.dotc.config.PathResolver$Environment$.searchForBootClasspath(PathResolver.scala:40)
Error:  	at dotty.tools.dotc.config.PathResolver$Environment$.javaBootClassPath(PathResolver.scala:49)
Error:  	at dotty.tools.dotc.config.PathResolver$Defaults$.javaBootClassPath(PathResolver.scala:75)
Error:  	at dotty.tools.dotc.config.CommonScalaSettings.$init$(ScalaSettings.scala:92)
Error:  	at dotty.tools.dotc.config.ScalaSettings.<init>(ScalaSettings.scala:33)
Error:  	at dotty.tools.dotc.config.ScalaSettings$.<init>(ScalaSettings.scala:30)
Error:  	at dotty.tools.dotc.config.ScalaSettings$.<clinit>(ScalaSettings.scala:30)
Error:  	... 9 more

I re-ran the job and it worked the second time.