Update welcome-to-2nd-line.html.md
Update welcome-to-2nd-line.html.md

Updated page owner to new delivery manager.

Added a Pager Duty link in first reference.

Edited a sentence.

alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs