Contribution checklist updates for copyright assignment changes

Contribution checklist updates for copyright assignment changes

[Siddhesh Poyarekar]

Hello,

Here's the suggested change to the "FSF Copyright Assignment" section in 
the contribution checklist to reflect the current state of our requirements:

"""
== Copyright ==

Even before you start developing your patch, you need to determine if 
you own copyright to your patch and if you have the right to contribute 
the patch to glibc under a compatible license.  To confirm that you 
indeed have the right (and agree) to contribute your patch, add a 
`Signed-off-by` line to your patch submission to provide a [Developer 
Certificate of Origin](https://developercertificate.org/).

Alternatively, you may choose to assign copyright for your changes to 
glibc to the Free Software Foundation.   If you wish to do so, an FSF 
project steward who can direct you to a FSF copyright assignment request 
form that's best suited to your contribution under the guidelines on 
this gnu.org webpage. To find a glibc maintainer or project steward see 
the MAINTAINERS page or ask for help on libc-help.

Note: the following list is quick reference links for developers and 
project stewards. They will send you the correct form.

  * request-disclaim.changes

  * request-assign.changes

  * request-assign.future

For GNU C Library Stewards: Template Email for Copyright assignment issues

"""

PS: Are the Signed-off-by and FSF assignment mutually exclusive?  It 
seems like the DCO doesn't actually deal with assignment and it may make 
sense to just have everyone add a S-o-b all the time to indicate their 
willingness and ability to contribute.