lib: Document that the filename is stored in the 'data' of a mail document

Our database schema documentation previously didn't give any
indication of where this most essential piece of information is
stored.

diff --git a/lib/database.cc b/lib/database.cc
index 7efd3b4ae3c1dea17833de6e1dba9f8cc9cbf536..f7f9943f8a5ac6e03e90c40640b9198d95a2b8cf 100644 (file)
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -75,6 +75,9 @@ typedef struct {
  * user in searching. But the database doesn't really care itself
  * about any of these.
  *
+ * Finally, the data portion of a mail document contains the path name
+ * of the mail message (relative to the database path).
+ *
  * Directory document
  * ------------------
  * A directory document is used by a client of the notmuch library to