Fix first step in release howto.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1453990 13f79535-47bb-0310-9956-ffa450edef68

Author: netomi

doc/release/release.howto.txt

@@ -21,7 +21,7 @@ Preliminary checks:
 As a first optional step, you can test that everything works locally, i.e.
 that the build process can create all the necessary artefacts. The command
 
-  $ mvn clean deploy -Prelease -Ptest-deploy
+  $ mvn clean deploy -Ptest-deploy
 
 should create the artefacts in the "target/deploy".