(doc) Fix parameter name
diff --git a/enforcer-rules/src/site/apt/requireEnvironmentVariable.apt.vm b/enforcer-rules/src/site/apt/requireEnvironmentVariable.apt.vm
index 21a3a8e..1ec072a 100644
--- a/enforcer-rules/src/site/apt/requireEnvironmentVariable.apt.vm
+++ b/enforcer-rules/src/site/apt/requireEnvironmentVariable.apt.vm
@@ -32,7 +32,7 @@
    
    * message - an optional message to the user if the rule fails.
    
-   * variableNames - The name of the environment variable to be checked for.
+   * variableName - The name of the environment variable to be checked for.
    
    []