[GOBBLIN-1354] Change homepage link in documentation to index.md for mkdocs build to pass on RTD
[GOBBLIN-1354] Change homepage link in documentation to index.md for mkdocs build to pass on RTD

Closes #3194 from abti/master

linkedin/gobblin,shirshanka/gobblin,arjun4084346/gobblin,jack-moseley/gobblin,shirshanka/gobblin,linkedin/gobblin,jack-moseley/gobblin,arjun4084346/gobblin,linkedin/gobblin,linkedin/gobblin,jack-moseley/gobblin,abti/gobblin,linkedin/gobblin,arjun4084346/gobblin,shirshanka/gobblin,abti/gobblin,jack-moseley/gobblin,arjun4084346/gobblin,shirshanka/gobblin,abti/gobblin,abti/gobblin,jack-moseley/gobblin,abti/gobblin,abti/gobblin,shirshanka/gobblin,arjun4084346/gobblin,linkedin/gobblin