Mention that `--crtimes` support is spotty.

diff --git a/rsync.1.md b/rsync.1.md
index ee0a4f39463dab133880643cbae0a0362608671c..16dbf20c22e526e1f4071a50683f5ddbc96513e7 100644 (file)
--- a/rsync.1.md
+++ b/rsync.1.md
@@ -1636,7 +1636,9 @@ expand it.
 0.  `--crtimes`, `-N,`
 
     This tells rsync to set the create times (newness) of the destination
-    files to the same value as the source files.
+    files to the same value as the source files. Your OS & filesystem must
+    support the setting of arbitrary creation (birth) times for this option
+    to be supported.
 
 0.  `--omit-dir-times`, `-O`