Fix documentation attributes bug

This commit addresses a bug (introduced by Ide4369ca194) related to
documentation attributes in the _genasciidoc_htmlonly_zip function.

Previously, a bug existed where the attributes argument was not being
populated correctly, leading to incomplete documentation attributes such
as "Table of Contents" and "revision version".

The root cause was the misuse of a ternary operator that failed to
modify the attributes list as intended, resulting in a mismatch between
expected and actual attributes.

Use parentheses to ensure proper order of operations and association
when populating the "attributes" argument.

This change guarantees that the intended attributes, including "Table of
Contents" and "revision version", are consistently appended to the
attributes list when needed.

Release-Notes: Fix documentation attributes bug
Change-Id: I872ddfdca0b2db6d5fbaa410719076f207abeb3c
(cherry picked from commit 6e1fc45eeaff7ad19f85da817bb99f609aa42912)
diff --git a/tools/bzl/asciidoc.bzl b/tools/bzl/asciidoc.bzl
index d6b6d63..703d5b7 100644
--- a/tools/bzl/asciidoc.bzl
+++ b/tools/bzl/asciidoc.bzl
@@ -307,7 +307,7 @@
     _genasciidoc_htmlonly_zip(
         name = name + SUFFIX if resources else name,
         srcs = srcs,
-        attributes = attributes + [] if webfonts else ["webfonts!"],
+        attributes = attributes + ([] if webfonts else ["webfonts!"]),
         backend = backend,
         searchbox = searchbox,
         **kwargs