Fix Button examples in spec v0.10 to use 'child' instead of 'text'

[selamw1]

This PR fixes a conflict in the v0.10 spec documentation by updating Button examples in a2ui_protocol.md to use the child property instead of text, aligning them with the required JSON schema in basic_catalog.json.

Fixes #1154

Pre-launch Checklist

• I signed the [CLA].
• I read the [Contributors Guide].
• I read the [Style Guide].
• I have added updates to the [CHANGELOG].
• I updated/added relevant documentation.
• My code changes (if any) have tests.

[gemini-code-assist]

Code Review

This pull request updates the a2ui_protocol.md documentation by adding id fields and replacing text properties with child properties in several Button component examples. The review feedback suggests adopting a more consistent naming convention for child component IDs, specifically following the [component_id]_label pattern to align with other examples in the documentation.

[gemini-code-assist]

For consistency with the main example stream (line 331) and the mermaid diagram description (line 373), it is recommended to use a more descriptive ID for the child component that follows the [component_id]_label pattern. Since the button ID is submit_button, the label ID should ideally be submit_button_label.

Suggested change

	"child": "submit_label",
	"child": "submit_button_label",

[gemini-code-assist]

Similar to the previous example, using a consistent naming convention for the child component ID (e.g., open_link_button_label) improves readability and aligns with the established patterns in this documentation.

Suggested change

	"child": "open_link_label",
	"child": "open_link_button_label",

[gemini-code-assist]

To maintain consistency with the earlier examples and the overall documentation style, consider using submit_button_label as the ID for the child component here as well.

Suggested change

	"child": "submit_label",
	"child": "submit_button_label",