Small grammar change to pull requests guide  (#4322)
Small grammar change to pull requests guide  (#4322)

him -> them, which is consistent with usage above.
TravisEz13/PowerShell,TravisEz13/PowerShell,TravisEz13/PowerShell,JamesWTruher/PowerShell-1,JamesWTruher/PowerShell-1,PaulHigin/PowerShell,daxian-dbw/PowerShell,PaulHigin/PowerShell,PaulHigin/PowerShell,PaulHigin/PowerShell,JamesWTruher/PowerShell-1,daxian-dbw/PowerShell,JamesWTruher/PowerShell-1,daxian-dbw/PowerShell,TravisEz13/PowerShell,daxian-dbw/PowerShell