Documentation: fix Bazel options for a Java 8 build

Update the dev-bazel.txt documentation with the correct
options to trigger a legacy Java 8 build.

Change-Id: Ib1f883207182bd9b1b0ed3ef8ef7e57db84967ef
diff --git a/Documentation/dev-bazel.txt b/Documentation/dev-bazel.txt
index 086e836..96cc67f 100644
--- a/Documentation/dev-bazel.txt
+++ b/Documentation/dev-bazel.txt
@@ -61,8 +61,7 @@
 in future gerrit releases. To build Gerrit with Java 8 language level, run:
 
 ```
-  $ bazel build --java_toolchain //tools:error_prone_warnings_toolchain_java8
-        :release
+  $ bazel build --java_toolchain //tools:error_prone_warnings_toolchain :release
 ```
 
 [[java-11]]