Check links throughout the documentation

[cdibella]

We've had multiple reports of broken links in recent days. Probably worth a check over the whole thing to see what 404s are lurking.

[mark-cooper]

Might be worth checking something like this with multiple tools to confirm the result, but broken-link-checker (scoped to 404) found:

Getting links from: https://archivesspace.github.io/tech-docs/readme_develop
├─BROKEN─ https://github.com/archivesspace/archivesspace/blob/master/CODE_OF_CONDUCT.html (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/readme_develop.html
├─BROKEN─ https://github.com/archivesspace/archivesspace/blob/master/CODE_OF_CONDUCT.html (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/migrations/migration_tools.html
├─BROKEN─ https://github.com/archivesspace-deprecated/ArchonMigrator/blob/master/README.html (HTTP_404)
├─BROKEN─ https://github.com/archivesspace/archivesspace/tree/master/backend/app/exporters/examples/accession (HTTP_404)
├─BROKEN─ https://github.com/archivesspace/archivesspace/tree/master/backend/app/exporters/examples/assessment (HTTP_404)
├─BROKEN─ https://github.com/archivesspace/archivesspace/tree/master/backend/app/exporters/examples/digital_object (HTTP_404)
├─BROKEN─ http://archivesspace.org/wp-content/uploads/2016/05/EAD-Import-Export-Mapping-20171030.xlsx (HTTP_404)
├─BROKEN─ https://github.com/archivesspace/archivesspace/tree/master/backend/app/exporters/examples/location (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/customization/configuration.html
├─BROKEN─ https://github.com/archivesspace/tech-docs/blob/master/provisioning/mysql.html (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/administration/upgrading.html
├─BROKEN─ https://archivesspace.github.io/tech-docs/administration/provisioning/solr.html (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/provisioning/tuning.html
├─BROKEN─ https://rtcamp.com/tutorials/mysql/tuningprimer/ (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/development/ui_test.html
├─BROKEN─ https://developer.mozilla.org/en-US/docs/Mozilla/QA/Marionette/WebDriver (HTTP_404)
├─BROKEN─ https://archivesspace.github.io/tech-docs/development/dev.md (HTTP_404)
Getting links from: https://archivesspace.github.io/tech-docs/development/vscode.html
├─BROKEN─ https://marketplace.visualstudio.com/items?itemName=dbaeumer.vscode-eslint (HTTP_404)
├─BROKEN─ https://marketplace.visualstudio.com/items?itemName=esbenp.prettier-vscode (HTTP_404)
├─BROKEN─ https://marketplace.visualstudio.com/items?itemName=LoranKloeze.ruby-rubocop-revived (HTTP_404)
├─BROKEN─ https://marketplace.visualstudio.com/items?itemName=stylelint.vscode-stylelint (HTTP_404)