Add accessibility statement to the documentation

[astroDimitrios]

📚 Documentation

Opening this to add the generic accessibility statement for generated documentation.
See https://github.com/MetOffice/common-fortran-template/issues/14 where I will add the statement first.

NOTE: This repo isn't public yet but the docs are, https://metoffice.github.io/common-fortran-template, and show the link to the statement in the footer.

[bjlittle]

@astroDimitrios Why do we need this?

[astroDimitrios]

@bjlittle Sorry I forgot to put the info here, as in https://github.com/MetOffice/common-fortran-template/issues/14 I have been in contact with Legal as part of the git / GitHub migration project. Specifically I asked about the legal requirement for websites of public bodies to provide an accessibility statement on their website and whether it applies to documentation (websites) generated through Sphinx (I gave IRIS as an example).

Legal got back and said we do need to provide one but a blanket statement for sites generated in this way should suffice. I will forward you the full email. I have checked the exemptions list (note the email has link to the old legislation which has now been superceeded/revoked) and it doesn't look like we would be exempt.

I will write the generic one as part of the migration project and then it can be copied across to other repos. In terms of why public bodies have to do this - I guess it's always good to consider accessibility and the pydata Sphinx theme IRIS uses is very good in terms of accessibility so adding this statement should suffice.

[trexfeathers]

@astroDimitrios we will happily adapt your accessibility statement once it is finalised. Already have some ideas on where we will put the link etc.

Thanks for raising ♥