fix: replace .Site.BaseURL with absURL in templates

[JTorreG]

Proposed changes

Replaces .Site.BaseURL with absURL as per https://gohugo.io/methods/site/baseurl/

for example:
<p><a href="https://www.f5.com/"><img class="f5-logo-footer" src="{{.Site.BaseURL}}/images/icons/Logo_F5.svg" alt="F5 logo"></a>

becomes

<p><a href="https://www.f5.com/"><img class="f5-logo-footer" src="{{ "/images/icons/Logo_F5.svg" | absURL }}" alt="F5 logo"></a>

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• I have updated any relevant documentation (README.md and CHANGELOG.md)