doc: Merge disjointed bits about emailing patches

We obviously prefer git-send-email(1), and the disjointed nature
of the two statements was misleading.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

doc/developer.texi

@@ -362,12 +362,6 @@ The tool is located in the tools directory.
 Run the @ref{Regression Tests} before submitting a patch in order to verify
 it does not cause unexpected problems.
 
-Patches should be posted as base64 encoded attachments (or any other
-encoding which ensures that the patch will not be trashed during
-transmission) to the
-@uref{https://lists.libav.org/mailman/listinfo/libav-devel, libav-devel}
-mailing list.
-
 It also helps quite a bit if you tell us what the patch does (for example
 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
 and has no lrint()'). This kind of explanation should be the body of the
@@ -376,8 +370,12 @@ commit message.
 Also please if you send several patches, send each patch as a separate mail,
 do not attach several unrelated patches to the same mail.
 
-Use @code{git send-email} when possible since it will properly send patches
-without requiring extra care.
+Patches should be posted to the
+@uref{https://lists.libav.org/mailman/listinfo/libav-devel, libav-devel}
+mailing list. Use @code{git send-email} when possible since it will properly
+send patches without requiring extra care. If you cannot, then send patches
+as base64-encoded attachments, so your patch is not trashed during
+transmission.
 
 Your patch will be reviewed on the mailing list. You will likely be asked
 to make some changes and are expected to send in an improved version that