Improve .gitignore

.gitignore

@@ -1,8 +1,20 @@
-target
-example-project/jmh.out
-project/target
-.idea
-.idea_modules
-hs_err*
-*.iml
-*.jfr
+### SBT template
+# Simple Build Tool
+# http://www.scala-sbt.org/release/docs/Getting-Started/Directories.html#configuring-version-control
+
+dist/*
+target/
+lib_managed/
+src_managed/
+project/boot/
+project/plugins/project/
+.history
+.cache
+.lib/
+
+### Scala template
+*.class
+*.log
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*