[PATCH] Documentation/git-send-email.txt: Mention less secure app access might need to enable.

[Vasyl Vavrychuk <vvavrychuk@gmail.com>]

Looks like Google changed Gmail security and now less secure app access
needs to be explicitly enabled if 2-factor authentication is not in
place, otherwise send-mail fails with:

  5.7.8 Username and Password not accepted. Learn more at
  5.7.8  https://support.google.com/mail/?p=BadCredentials v5sm13756502ede.13 - gsmtp

Signed-off-by: Vasyl Vavrychuk <vvavrychuk@gmail.com>
---
 Documentation/git-send-email.txt | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 0a69810147..06953fd1e0 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -494,7 +494,11 @@ edit ~/.gitconfig to specify your account settings:
 	smtpServerPort = 587
 ----
 
-If you have multifactor authentication setup on your gmail account, you will
+If you do not have multi-factor authentication set up on your Gmail account, you
+will need to allow less secure app access. Visit
+https://myaccount.google.com/lesssecureapps to enable it.
+
+If you have multi-factor authentication set up on your Gmail account, you will
 need to generate an app-specific password for use with 'git send-email'. Visit
 https://security.google.com/settings/security/apppasswords to create it.
 
-- 
2.23.0