Improve user login experience by adding metadata which can be displayed in the IdP login flow

[SteelWagstaff]

A user writes:

A Shibboleth IdP supports echoing data in the metadata onto its login screen. You may want to look into adding these data elements to your metadata generation process:

1. If you add xmlns:mdui="urn:oasis:names:tc:SAML:metadata:ui" to the <md:EntityDescriptor entityID=...... line before the closing >
2. Then add the following lines after the line starting with:

<md:SPSSODescriptor ...................>
     <md:Extensions>
        <mdui:UIInfo>
            <mdui:DisplayName xml:lang="en">Pressbooks EDU</mdui:DisplayName>
            <mdui:InformationURL xml:lang="en">https://.....................................................</mdui:InformationURL>
            <mdui:PrivacyStatementURL xml:lang="en">https://.........................................................</mdui:PrivacyStatementURL>
            <mdui:Logo height="65" width="161" xml:lang="en">https://pressbooks.org/app/uploads/2018/01/opengraph.png</mdui:Logo>
        </mdui:UIInfo>

The mdui claim has other elements that can be added. The results make the login page look like: