Re: [PATCH v4 2/3] docs: improve send-email documentation

> -EXAMPLES
> ---------
> -Use gmail as the smtp server
> +EXAMPLES OF SMTP SERVERS
> +------------------------
> +Use Gmail as the SMTP Server

>  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> -To use 'git send-email' to send your patches through the GMail SMTP server,
> -edit ~/.gitconfig to specify your account settings:
> +To use 'git send-email' to send your patches through the Gmail SMTP server,
> +edit '~/.gitconfig' to specify your account settings:

> @@ -528,6 +528,37 @@ If you have multi-factor authentication set up on your Gmail account, you can
>  generate an app-specific password for use with 'git send-email'. Visit
>  https://security.google.com/settings/security/apppasswords to create it.
>  
> +You can also use OAuth2.0 authentication with Gmail. To do this, edit your
> +`~/.gitconfig` file and add `smtpAuth = OAUTHBEARER` to your account settings:
> +
> +----
> +[sendemail]
> +	smtpEncryption = tls
> +	smtpServer = smtp.gmail.com
> +	smtpUser = yourname@gmail.com
> +	smtpServerPort = 587
> +	smtpAuth = OAUTHBEARER
> +----
> +
> +Use Microsoft Outlook as the SMTP Server
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +Unlike Gmail, Microsoft Outlook no longer supports app-specific passwords.
> +Therefore, OAuth2.0 authentication must be used for Outlook.
> +
> +Edit '~/.gitconfig' to specify your account settings for Outlook and use its
> +SMTP server with 'git send-email':
> +
> +----
> +[sendemail]
> +	smtpEncryption = tls
> +	smtpServer = smtp.office365.com
> +	smtpUser = yourname@outlook.com
> +	smtpServerPort = 587
> +	smtpAuth = XOAUTH2
> +----

> +SENDING PATCHES
> +---------------
>  Once your commits are ready to be sent to the mailing list, run the
>  following commands:
>  
> @@ -536,9 +567,23 @@ following commands:
>  	$ git send-email outgoing/*
>  
>  The first time you run it, you will be prompted for your credentials.  Enter the
> -app-specific or your regular password as appropriate.  If you have credential
> -helper configured (see linkgit:git-credential[1]), the password will be saved in
> -the credential store so you won't have to type it the next time.
> +app-specific or your regular password as appropriate.
> +
> +If you have a credential helper configured (see linkgit:git-credential[1]), the
> +password will be saved in the credential store so you won't have to type it the
> +next time.
> +
> +If you are using OAuth2.0 authentication, you need to use an access token in
> +place of a password when prompted. Various OAuth2.0 token generators are
> +available online. Community maintained credential helpers for Gmail and Outlook
> +are also available:
> +
> +	- https://github.com/AdityaGarg8/git-credential-email[git-credential-gmail] (cross platform, dedicated helper for authenticating Gmail accounts)
> +
> +	- https://github.com/AdityaGarg8/git-credential-email[git-credential-outlook] (cross platform, dedicated helper for authenticating Microsoft Outlook accounts)