docs: Reviewed and modified the new contents + modified the icons in the sidebar

[balaharish7]

No description provided.

[balaharish7]

14-Mar-24: @avishnu @Abhinandan-Purkait @niladrih @datacore-gthomas

We have modified & the reviewed the 1st two sections (Introduction to OpenEBS & Concepts).
Kindly verify and share your feedback, if any by EOB 15-Mar-24. :-)

[orville-wright]

Looks good. I personally think we should not repeat the word "Guide" everywhere in the tree view (if possible).

[balaharish7]

We have modified & the reviewed the Troubleshooting section.
Kindly verify and share your feedback.

[balaharish7]

19-Mar-24: @avishnu @Abhinandan-Purkait @niladrih @datacore-gthomas

We have modified & the reviewed the below sections:

• QuickStart Guide
  - QuickStart
  - Installation
  - Deploy a Test Application
• FAQs
• Community
• Commercial Support

Note: Deploy a Test Application section contains the Mayastor Configuring docs as well. We need the contents for Deploy a Test Application & Configuration of Local Engine.
Based on our review, we would suggest we can have a separate page for Deployment and a separate page for Configuration.

Kindly verify and share your feedback.

[balaharish7]

20-Mar-24: @avishnu @Abhinandan-Purkait @niladrih @datacore-gthomas

We have modified & the reviewed the below sections:

• Local Engine Prerequisites
• Local Engine Installation

Kindly verify and share your feedback.

[avishnu]

Looks good at the outset. Need to validate once on the live website.