Replace 'SBT' with 'sbt'

Author: Philippus

README.md

@@ -19,8 +19,8 @@ As of Scala 2.11, this library is a separate jar that can be omitted from Scala
  * A more complicated example, [Building a lexer and parser with Scala's Parser Combinators](https://enear.github.io/2016/03/31/parser-combinators/)
  * "Combinator Parsing", chapter 33 of [_Programming in Scala, Third Edition_](http://www.artima.com/shop/programming_in_scala), shows how to use this library to parse arithmetic expressions and JSON. The second half of the chapter examines how the library is implemented.
 
-## Adding an SBT dependency
-To depend on scala-parser-combinators in SBT, add something like this to your build.sbt:
+## Adding an sbt dependency
+To depend on scala-parser-combinators in sbt, add something like this to your build.sbt:
 
 ```
 libraryDependencies += "org.scala-lang.modules" %% "scala-parser-combinators" % "1.1.2"