Correct indentation to appease markdownlint

[fredden]

Purpose of this pull request

This pull request fixes complaints from markdownlint as seen in the 'super-lint' GitHub Action. After opening https://github.com/magento/devdocs/pull/9519, I noticed that there were complaints in one of the changed files (but not related to that pull request) which prevents that from being merged. Having run markdownlint on all files in src/, these are the only changes required for a clean result. It turns out that only white-space changes were required to appease the linter; viewing this pull request with "ignore white-space" should show no changes.

src/guides/v2.3/get-started/create-integration.md:69 MD032/blanks-around-lists Lists should be surrounded by blank lines [Context: "<!--"] src/guides/v2.3/get-started/create-integration.md:82 MD040/fenced-code-language Fenced code blocks should have a language specified [Context: " ```"] src/guides/v2.3/get-started/create-integration.md:110 MD046/code-block-style Code block style [Expected: fenced; Actual: indented]

Affected DevDocs pages

• https://devdocs.magento.com/guides/v2.3/get-started/create-integration.html

[dshevtsov]

@magento import code to magento-devdocs/devdocs

[m2-github-services]

@dshevtsov the branch with the code is successfully imported into the magento-devdocs/devdocs repository. Branch name: imported-fredden-magento-devdocs-9520.