Fix numbering for PagerDuty manual running instructions
Fix numbering for PagerDuty manual running instructions

These were previously being rendered as 1., 1. and 1. since the code was
not indented. Also changing to number all as `1.` in the markdown so the
rendering can number themselves while reducing the git diff when extra
lines are added.

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