make links more descriptive

fixes PLAT-583

test plan:
the links on the App Setting page for eduappcenter and Canvas community topics for lti tools should be more descriptive

Change-Id: I066a6181ee60daa6e4200b2737c799f7976f4bed
Reviewed-on: https://gerrit.instructure.com/38777
Reviewed-by: Brad Humphrey <brad@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Nathan Mills <nathanm@instructure.com>