update git-pull-request.1

man/git-pull-request.1

@@ -19,7 +19,7 @@ A personal access token is required for making the API call to open the pull req
 Make sure the personal access token has the right \fBOAuth\fR scopes for the repo(s)
 .
 .P
-Use \fBgit config \-\-global \-\-add git\-extras\.github\-personal\-access\-token <your\-personal\-access\-token>\fR
+Use \fBGITHUB_TOKEN\fR environment variable, or \fBgit config \-\-global \-\-add git\-extras\.github\-personal\-access\-token <your\-personal\-access\-token>\fR
 .
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 If using multiple accounts, override the global value in the specific repo using \fBgit config git\-extras\.github\-personal\-access\-token <other\-acc\-personal\-access\-token>\fR