docs/Tsumitsu Fix render issue in GFM documentation page

What does this MR do?

Fixes the render issues of git flavoured markdown documentation page by replacing markdown snippets having render issue in docs site by either HTML or images

Related issues

https://gitlab.com/gitlab-org/gitlab-ce/issues/43969

Closes

Author's checklist

• Apply the correct labels and milestone
• Crosslink the document from the higher-level index
• Crosslink the document from other subject-related docs
• Correctly apply the product badges and tiers
• Port the MR to EE (or backport from CE): always recommended, required when the ee-compat-check job fails

Review checklist

• Your team's review (required)
• PM's review (recommended, but not a blocker)
• Technical writer's review (required)
• Merge the EE-MR first, CE-MR afterwards

/label ~Documentation