[v14] Fix docs markup errors

[iAdramelk]

Some fixes for the docs to fix validation errors and warnings in Docusaurus:

• Remove duplicate redirects.
• Remove redirects form existing pages.
• Update redirects leading to non-existing pages.
• Fix damaged svg image (can't read width and height).
• Add .mdx extension to links to make possible to validate links.
• Fixed typo in docs/pages/reference/terraform-provider.mdx that was causing mdx failing. (But this is an auto-generated file, so it's better to fix it in the original location too).

[CLAassistant]

All committers have signed the CLA.

[ptgott]

Going to create a buddy PR for this one