Get rid of repeated use of 'configuration' in opening para

Author: asb

llvm/docs/HowToAddABuilder.rst

@@ -183,9 +183,9 @@ Testing a Builder Config Locally
 ================================
 
 It is possible to test a builder running against a local version of LLVM's
-buildmaster configuration. This allows you to test changes to builder,
-worker, and buildmaster configuration. A buildmaster launched in this "local
-testing" mode will:
+buildmaster setup. This allows you to test changes to builder, worker, and
+buildmaster configuration. A buildmaster launched in this "local testing" mode
+will:
 * Bind only to local interfaces.
 * Use SQLite as the database.
 * Use a single fixed password for workers.