add comments to example conf file to warn about common filter line mistakes

diff --git a/doc/example.conf b/doc/example.conf
index 8fc3e53726da94785ade2d47d3ba96ff8e1b466f..c44c6a7a090370c8f2006345f03a9adeafd2e05c 100644 (file)
--- a/doc/example.conf
+++ b/doc/example.conf
@@ -33,8 +33,12 @@ devices {
     # pattern, the device is accepted; otherwise if any name matches any 'r'
     # pattern it is rejected; otherwise it is accepted.
 
-    # Remember to run vgscan after you change this parameter to ensure 
-    # that the cache file gets regenerated (see below).
+    # Don't have more than one filter line active at once: only one gets used.
+
+    # Run vgscan after you change this parameter to ensure that
+    # the cache file gets regenerated (see below).
+    # If it doesn't do what you expect, check the output of 'vgscan -vvvv'.
+
 
     # By default we accept every block device:
     filter = [ "a/.*/" ]