docs: fix step numbering and artifact naming consistency in README

- Change TLDR step numbering from 2,3,4,5 to 0,1,2,3 to match detailed sections
- Update artifact naming from concrete example to pattern notation (00N-SYSTEM.md)
- Add clarifying note to workflow diagram about optional context generation phase

Resolves CodeRabbit review comments (1 duplicate + 2 nitpicks)

Co-authored-by: Gregg Coppen <[email protected]>

Author: github-actions[bot]

README.md

@@ -23,28 +23,28 @@
     uvx --from git+https://github.com/liatrio-labs/spec-driven-workflow sdd-generate-commands generate --yes
     ```
 
-2. *(Optional, first time)* Run `/generate-context` to analyze your existing codebase:
+0. *(Optional, first time)* Run `/generate-context` to analyze your existing codebase:
 
     ```text
     /generate-context
     ```
 
-    → AI analyzes your codebase → Context document created in `docs/001-SYSTEM.md` (or `002-SYSTEM.md`, etc.)
+    → AI analyzes your codebase → Context document created in `docs/00N-SYSTEM.md` (e.g., `001-SYSTEM.md`, `002-SYSTEM.md`, etc.)
 
-3. In your AI tool of choice, use `/generate-spec` with your idea:
+1. In your AI tool of choice, use `/generate-spec` with your idea:
 
     ```text
     /generate-spec I want to add user authentication to my app
     ```
 
     → AI asks clarifying questions → You provide answers → Spec created in `tasks/0001-spec-user-auth.md`
 
-4. Continue the flow:
+2. Continue the flow:
 
     - Run `/generate-task-list-from-spec` → Task list created in `tasks/tasks-0001-spec-user-auth.md`
     - Use `/manage-tasks` → Execute tasks one-by-one with proof artifacts
 
-5. **SHIP IT** 🚢💨
+3. **SHIP IT** 🚢💨
 
 ## Highlights
 
@@ -122,6 +122,8 @@ Four prompts in `/prompts` define the full lifecycle. Use them sequentially to m
 
 ### Detailed SDD Workflow Diagram
 
+> **Note:** This diagram shows the core workflow (stages 1-3). The optional context generation phase (stage 0: `/generate-context`) precedes this flow when analyzing an existing codebase.
+
 ```mermaid
 sequenceDiagram
   participant U as User