docs: fix outdated /speckit.* command references to /spec.*

Fixes #35

- docs/quickstart.md: /speckit.tasks -> /spec.tasks (lines 341, 344)
- templates/commands/checklist.md: /speckit.checklist -> /spec.checklist (line 303)

Author: kanfil

docs/quickstart.md

@@ -338,10 +338,10 @@ Be specific about your tech stack and technical requirements:
 
 ### Step 6: Define Tasks
 
-Generate an actionable task list using the `/speckit.tasks` command:
+Generate an actionable task list using the `/spec.tasks` command:
 
 ```bash
-/speckit.tasks
+/spec.tasks
 ```
 
 ### Step 7: Validate and Implement

templates/commands/checklist.md

@@ -300,7 +300,7 @@ You **MUST** consider the user input before proceeding (if not empty).
    - MCP configuration validation status (if included in checklist)
    - Framework options validation status (based on enabled mode options)
 
-**Important**: Each `/speckit.checklist` command invocation uses a short, descriptive checklist filename and either creates a new file or appends to an existing one. This allows:
+**Important**: Each `/spec.checklist` command invocation uses a short, descriptive checklist filename and either creates a new file or appends to an existing one. This allows:
 
 - Multiple checklists of different types (e.g., `ux.md`, `test.md`, `security.md`)
 - Simple, memorable filenames that indicate checklist purpose