Merge workflow.md and sbt.md

Author: anatoliykmetyuk

docs/docs/contributing/tools/sbt.md

@@ -64,3 +64,15 @@ u: dotty.tools.dotc.core.Types.Type = TypeBounds(TypeRef(ThisType(TypeRef(NoPref
 Many objects in the dotc compiler implement a `Showable` trait (e.g. `Tree`,
 `Symbol`, `Type`). These objects may be prettyprinted using the `.show`
 method
+
+## SBT Commands Cheat Sheet ##
+The basics of working with Dotty codebase are documented [here](http://dotty.epfl.ch/docs/contributing/getting-started.html) and [here](http://dotty.epfl.ch/docs/contributing/workflow.html). Below is a cheat sheet of some frequently used commands (to be used from SBT console – `sbt`).
+
+
+|                        Command                       |                                                          Description                                                          |
+|------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------|
+| `dotc ../issues/Playground.scala`                    | Compile the given file – path relative to the Dotty directory. Output the compiled class files to the Dotty directory itself. |
+| `dotr Playground`                                    | Run the compiled class `Playground`. Dotty directory is on classpath by default.                                              |
+| `repl`                                               | Start REPL                                                                                                                    |
+| `testOnly dotty.tools.dotc.CompilationTests -- *pos` | Run test (method) `pos` from `CompilationTests` suite.                                                                        |
+| `testCompilation sample`                             | In all test suites, run test files containing the word `sample` in their title.                                               |