Add metrics collection and metrics-based dashboards info to HAProxy Otel app

[yasar-sumologic]

…Tel app doc

Purpose of this pull request

Changes to haproxy-otel app doc after changes in it to add metric collection and metric-based dashboards

Select the type of change

• Minor Changes - Typos, formatting, slight revisions
• Update Content - Revisions, updating sections
• New Content - New features, sections, pages, tutorials
• Site and Tools - .clabot, version updates, maintenance, dependencies, new packages for the site (Docusaurus, Gatsby, React, etc.)

Ticket (if applicable)

[cla-bot]

Thank you for your contribution! As this is an open source project, we require contributors to sign our Contributor License Agreement and do not have yours on file. To proceed with your PR, please sign your name here and we'll add you to our approved list of contributors.

[kimsauce]

minor changes!

[JV0812]

Minor fixes

[JV0812]

LGTM

[sumoanema]

@kimsauce - Could you please have look at this PR.

[kimsauce]

Could you please have look at this PR.

@sumoanema all set! Looks good.