fix(Edge_AI_Gallery_User_Guide): Standardize RST file section headers per Sphinx guidelines

* Update section headers in Edge_AI_Gallery_User_Guide.rst to follow
the Sphinx recommended hierarchy and formatting style as documented in [0]

[0] - https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#sections

Signed-off-by: Chirag Shilwant <[email protected]>

Author: cshilwant

source/linux/Demo_User_Guides/Edge_AI_Gallery_User_Guide.rst

@@ -1,17 +1,20 @@
 .. _Edge-AI-Gallery-User-Guide-label:
 
+############################
 Edge AI Gallery - User Guide
-============================
+############################
 
+********
 Overview
---------
+********
 
 The |__PART_FAMILY_DEVICE_NAMES__| SK board has a QT based Out of Box application setup so that user can test the prepackaged models, with sample images, videos and optionally with a connected camera. The Demo also allows users to add their custom models, images, and videos to extend the functionality.
 
 All of the necessary equipment requirement and instructions are provided here.
 
+**********************
 Hardware Prerequisites
-----------------------
+**********************
 
 - TI |__PART_FAMILY_DEVICE_NAMES__| SK
 
@@ -27,8 +30,9 @@ Hardware Prerequisites
 
 - Ethernet connection (if serial terminal console is not accessible)
 
+***************************************
 Launching and Using the edge AI gallery
----------------------------------------
+***************************************
 
 The edge AI gallery launches on Linux startup. Follow the below instructions to use it.
 
@@ -146,8 +150,9 @@ The edge AI gallery launches on Linux startup. Follow the below instructions to
 
    13. For more information on edge AI software stack, refer `Edge AI Documentation <https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-edgeai/AM69A/10_01_00/exports/docs/common/sdk_overview.html>`_
 
+************************
 Compiling EdgeAI GUI App
-========================
+************************
 
 The ideal way to compile EdgeAI GUI App is to trigger a Yocto
 build. But for a quicker way to do it, especially during development,