Update Readme - drop reference, update links, fix formatting

[rwaffen]

• drop reference part and link to reference.md
• update format
• Update ci link

[zilchms]

LGTM, OL7 changes seem unrelated. wo got those quite often on this module without actual changes :/

[alexjfisher]

I wonder if the test failures are because the service takes a long time to start due to a lack of entropy in the container environment when generating keys???

No SSL keys/certificates found in datadir (/var/lib/proxysql). Generating new keys/certificates

[zilchms]

Might be, at the same time the OL7 stuff dies by non-root PID. Definitly something that should be investigated, but I am missing the experience/knowledge to do that