style/standardize markdown lists miniapps

[Earnwithalee7890]

What changed? Why?
Standardized markdown list bullets from * to - in mini-app troubleshooting documentation (testing.mdx and error-handling.mdx).
Consistent hyphen-based lists improve readability and align with the Base docs markdown style guide.

Notes to reviewers

• Targeted only unordered list items in the mini-apps/troubleshooting/ directory.
• No content changes, only bullet style standardization (* → -).
• Verified that ordered lists (numbered) were left unchanged.

How has it been tested?

• Manual verification of affected files to ensure correct list syntax.
• Confirmed that the changes render correctly in Mintlify preview with mint dev.
• Checked that no other markdown elements (headers, code blocks) were inadvertently modified.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/2	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2