Clarify non-flag arguments for --compile_one_dependency.

PiperOrigin-RevId: 372088071
diff --git a/site/docs/user-manual.html b/site/docs/user-manual.html
index 9e9d340..2bc3e31 100644
--- a/site/docs/user-manual.html
+++ b/site/docs/user-manual.html
@@ -1165,8 +1165,9 @@
   syntax checking source files in IDEs, for example, by rebuilding a single
   target that depends on the source file to detect errors as early as
   possible in the edit/build/test cycle. This argument affects the way all
-  non-flag arguments are interpreted: for each source filename, one
-  rule that depends on it will be built. For
+  non-flag arguments are interpreted: each argument must be a
+  file target label or a plain filename relative to the current working
+  directory, and one rule that depends on each source filename is built. For
 
   C++ and Java
   sources, rules in the same language space are preferentially chosen. For