add an add-api-version Claude skill

.claude/skills/add-api-version/SKILL.md

@@ -0,0 +1,35 @@
+---
+name: add-api-version
+description: Add a new version to a Dropshot API. Use when the user wants to add a new API version or make versioned changes to an API.
+---
+
+# Add API version
+
+Add a new version to a Dropshot API in this repository.
+
+## Instructions
+
+Follow these steps in order. Do not skip ahead.
+
+### Step 1: Fetch the guide
+
+Fetch the guide from the dropshot-api-manager repository:
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/oxidecomputer/dropshot-api-manager/refs/heads/main/guides/new-version.md
+```
+
+**Do not summarize the guide.** Read and follow it exactly as written. Remember to fetch RFD 619 for context.
+
+### Step 2: Ascertain the scope of the request
+
+If not already provided, ask the user:
+
+* Which API they would like to change.
+* What changes to make.
+
+### Step 3: Make the change
+
+Follow the guide carefully and systematically to add a new version to the provided API which makes the given changes.
+
+Follow the guide step by step; do not skip any steps.