The "Edit this page on github" link should be less prominent on the ILDH

[greatislander]

Describe the bug

On the Inclusive Learning Design Handbook, the "Edit this page on github" should be less prominent.
Instead some thought should be given to:

1. Whether this link is relevant to users. Perhaps a link to contributor's guide is more appropriate.
2. If the link stays, consider making it less obvious and less prominent.

To reproduce

Not applicable.

Expected behavior

Not applicable.

Screenshots

Not applicable.

Technical details

Not applicable.

Additional context or notes

Migrated from https://issues.fluidproject.org/browse/ILDH-10.