add docs/guide.md, update skill structure, add guide reference to all workflows

claw-skills/docs/guide.md

@@ -0,0 +1,27 @@
+# Skill Authoring Guide
+
+## Skill Structure
+
+A skill is a directory with the following layout:
+
+```
+{skill-name}/SKILL.md          # Required — skill description and usage
+{skill-name}/scripts/         # Optional — executable scripts
+{skill-name}/workflows/        # Optional — process guides
+{skill-name}/docs/            # Optional — supplementary documentation
+```
+
+## Writing Requirements
+
+**SKILL.md should be concise.** It serves as a table of contents for workflows — list each workflow file path with the scenario that triggers it.
+
+> **All skill-related documentation must be written in English.**
+
+## Script Hint
+
+When a script needs to behave differently based on the calling agent, use these environment variables:
+
+- `AGENT_ID` — the agent ID executing the script
+- `AGENT_WORKSPACE` — the workspace of the agent executing the script
+
+For more agent info, call `ego-mgr get <column>` inside the script.