range-diff doc: add a section about output stability

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 4f3efde80cd8e4f0b1a5b6699ad3e569f19ca516..465a4ecbeddaa20189bce6e223df8bbfa0319b9a 100644 (file)
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -137,15 +137,17 @@ Note that no attempts whatsoever are made to validate the encoding.
        Specify encoding of compose message. Default is the value of the
        'sendemail.composeencoding'; if that is unspecified, UTF-8 is assumed.
 
---transfer-encoding=(7bit|8bit|quoted-printable|base64)::
+--transfer-encoding=(7bit|8bit|quoted-printable|base64|auto)::
        Specify the transfer encoding to be used to send the message over SMTP.
        7bit will fail upon encountering a non-ASCII message.  quoted-printable
        can be useful when the repository contains files that contain carriage
        returns, but makes the raw patch email file (as saved from a MUA) much
        harder to inspect manually.  base64 is even more fool proof, but also
-       even more opaque.  Default is the value of the `sendemail.transferEncoding`
-       configuration value; if that is unspecified, git will use 8bit and not
-       add a Content-Transfer-Encoding header.
+       even more opaque.  auto will use 8bit when possible, and quoted-printable
+       otherwise.
++
+Default is the value of the `sendemail.transferEncoding` configuration
+value; if that is unspecified, default to `auto`.
 
 --xmailer::
 --no-xmailer::
@@ -398,8 +400,11 @@ have been specified, in which case default to 'compose'.
 +
 --
                *       Invoke the sendemail-validate hook if present (see linkgit:githooks[5]).
-               *       Warn of patches that contain lines longer than 998 characters; this
-                       is due to SMTP limits as described by http://www.ietf.org/rfc/rfc2821.txt.
+               *       Warn of patches that contain lines longer than
+                       998 characters unless a suitable transfer encoding
+                       ('auto', 'base64', or 'quoted-printable') is used;
+                       this is due to SMTP limits as described by
+                       http://www.ietf.org/rfc/rfc5322.txt.
 --
 +
 Default is the value of `sendemail.validate`; if this is not set,