FLUT-996020 - [Others] Added user guidelines for custom plotband feature.

[BPraveenBalu]

Description

Prepared and added user guide documentation for the custom plotband, introducing two new methods to override and customize its appearance and text, along with images illustrating both public methods.

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: FLUT-996020-Plotband-ug

[SyncfusionBuild]

CI Status: FAILURE ❌
Source Compilation: SUCCESS ✅
Failure Reason: CI Failure with violation
Build Location: FLUT-996020-Plotband-ug
Technical Error(s): 0
Spelling Error(s): 5
Image Alt Text Error(s): 0
Image Size Error(s): 0
Image Name Error(s): 0
Front matter Error(s): 0
File Path Error(s): 0
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0
MD Tag Validation Error(s): 0

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: FLUT-996020-Plotband-ug

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: FLUT-996020-Plotband-ug
Technical Error(s): 0
Spelling Error(s): 0
Image Alt Text Error(s): 0
Image Size Error(s): 0
Image Name Error(s): 0
Front matter Error(s): 0
File Path Error(s): 0
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0
MD Tag Validation Error(s): 0