Clean up README to follow RST syntax better
Clean up README to follow RST syntax better

Clean up code blocks to follow RST syntax properly
Fix any missing inline code formatting
Fix inline links that remained in Markdown syntax
MeetMe/newrelic-plugin-agent,notnmeyer/newrelic-plugin-agent,alonisser/newrelic-plugin-agent,ModusCreateOrg/newrelic-plugin-agent,whiteear/newrelic-plugin-agent,notnmeyer/newrelic-plugin-agent,whiteear/newrelic-plugin-agent,ModusCreateOrg/newrelic-plugin-agent,whiteear/newrelic-plugin-agent,NewRelic-Python-Plugins/newrelic-python-agent,NewRelic-Python-Plugins/newrelic-python-agent,notnmeyer/newrelic-plugin-agent,alonisser/newrelic-plugin-agent,alonisser/newrelic-plugin-agent,MeetMe/newrelic-plugin-agent,rounds/newrelic-plugin-agent,rounds/newrelic-plugin-agent,ModusCreateOrg/newrelic-plugin-agent,rounds/newrelic-plugin-agent,MeetMe/newrelic-plugin-agent,NewRelic-Python-Plugins/newrelic-python-agent