Add blog post introducing the new golang-otel template

[welteki]

Description

Add blog post introducing the new golang-otel template

Motivation and Context

Announce the new golang-otel template and show how it can be used to improve observability for Golang functions.

Have you applied the editorial and style guide to your post?

See the README.md

How have you tested the instructions for any tutorial steps?

Types of changes

• New blog post
• Updating an existing blog post
• Updating part of an existing page
• Adding a new page

Checklist:

• I have given attribution for any images I have used and have permission to use them under Copyright law
• My code follows the writing-style of the publication and I have checked this
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s

[welteki]

Thanks for the review @rgee0. I have pushed changes to add your suggestions.