[geary/wip/713006-better-error-reporting: 2/2] Add doc comments for Geary.SmtpError.

[Michael Gratton <mjog src gnome org>]

commit 36092d4a9c73b63bf2226efc1e83517198874fa7
Author: Michael James Gratton <mike vee net>
Date:   Mon Nov 13 23:35:44 2017 +1100

    Add doc comments for Geary.SmtpError.

 src/engine/smtp/smtp-error.vala |   31 +++++++++++++++++++++++++------
 1 files changed, 25 insertions(+), 6 deletions(-)
---
diff --git a/src/engine/smtp/smtp-error.vala b/src/engine/smtp/smtp-error.vala
index 97f34f2..e7d3bd8 100644
--- a/src/engine/smtp/smtp-error.vala
+++ b/src/engine/smtp/smtp-error.vala
@@ -4,14 +4,33 @@
  * (version 2.1 or later).  See the COPYING file in this distribution.
  */
 
+
+/**
+ * Thrown when an error occurs communicating with a SMTP server.
+ */
 public errordomain Geary.SmtpError {
-    PARSE_ERROR,
-    STARTTLS_FAILED,
-    AUTHENTICATION_FAILED,
-    SERVER_ERROR,
+
+    /** The client already has a connection to the server. */
     ALREADY_CONNECTED,
+
+    /** The credentials presented for authentication were rejected. */
+    AUTHENTICATION_FAILED,
+
+    /** The client does not have a connection to the server. */
     NOT_CONNECTED,
+
+    /** The server does not support an SMTP feature required by the engine. */
+    NOT_SUPPORTED,
+
+    /** A response from the server could not be parsed. */
+    PARSE_ERROR,
+
+    /** A message could not be sent because a field required by SMTP was missing. */
     REQUIRED_FIELD,
-    NOT_SUPPORTED
-}
 
+    /** The server reported an error. */
+    SERVER_ERROR,
+
+    /** Establishing STARTTLS  was attempted, but failed. */
+    STARTTLS_FAILED
+}