Fix stray backtick in markdown documentation (#1761)

README.md

diff --git a/README.md b/README.md
index 4acb6d0..976e97c 100644
--- a/README.md
+++ b/README.md
@@ -98,7 +98,7 @@
 
 ## Using the formatter as a library
 
-The `dart_style package exposes a simple [library API][] for formatting code.
+The dart_style package exposes a simple [library API][] for formatting code.
 Basic usage looks like this:
 
 [library api]: https://pub.dev/documentation/dart_style/latest/