capitalization, typo
remove dead link
use terminology consistent with page title
typos
add link in again, with correct link this time
remove one more usage of "sub domain"
"development and testing environments" is a better link description
Linking from "development and testing" does not make sense - someone using assistive technology might ask "development and testing of what?". It makes more sense to link from the full phrase "development and testing environments" as that adequately describes the content of the link referred to.
Make the link about robots.txt explanatory
GDS -> Government Digital Service
grammar
service owner -> service manager
Fix "the GDS" grammar
Merge pull request #44 from alphagov/operating-subdomain-editing

copyediting for "operating a service.gov.uk subdomain"