Add Documentation for CapStyle and GapRatio in Doughnut Chart

[Vallarasu4653]

Description:

This PR adds documentation for the CapStyle and GapRatio (Spacing) properties for the Doughnut Chart in the Syncfusion .NET MAUI Toolkit Chart control. It includes detailed explanations, code examples, and visual illustrations to help users effectively utilize these features.

Changes Include:

• Added a section on the CapStyle property with explanations and examples of the different cap styles available.
• Included details on how to customize cap styles for smoother curves.
• Added a section on the GapRatio property to explain how to manage spacing between doughnut segments.
• Provided both XAML and C# code examples to demonstrate implementation for both properties.

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: UG-capstyle-spacing-support

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: UG-capstyle-spacing-support
Technical Error(s): 0
Spelling Error(s): 0
Image Alt Text Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
Image Size Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
Image Name Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
Front matter Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
File Path Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
CodeSnippet File Path Missing Error(s): 0
Toc Anchor Tags Validation Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)
MD Tag Validation Error(s): 0 (Critical: 0, High: 0, Medium: 0, Low: 0, Info: 0)

[VimalaThirumalaiKumarSF3739]

@Vallarasu4653 as its public repo, remove task id from pr template

[SyncfusionBuild]

Build Status: INPROGRESS 🔃
Build Location: UG-capstyle-spacing-support

[SyncfusionBuild]

CI Status: SUCCESS ✅
Source Compilation: SUCCESS ✅
Build Location: UG-capstyle-spacing-support
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

[VimalaThirumalaiKumarSF3739]

Changes fine, need to include images