feat: [workflows] clarify when dynamic step names can be used

src/content/docs/workflows/build/rules-of-workflows.mdx

@@ -229,6 +229,8 @@ export class MyWorkflow extends WorkflowEntrypoint {
 
 Dynamically naming a step will prevent it from being cached, and cause the step to be re-run unnecessarily. Step names act as the "cache key" in your Workflow.
 
+Note that, step names can be formed dynamically as long they are deterministic across steps and/or Workflow restarts.
+
 ```ts
 export class MyWorkflow extends WorkflowEntrypoint {
 	async run(event: WorkflowEvent<Params>, step: WorkflowStep) {
@@ -243,7 +245,20 @@ export class MyWorkflow extends WorkflowEntrypoint {
 		// Return dynamic values in your state, or log them instead.
 		let state = await step.do("fetch user data from KV", async () => {
 		    let userData = await env.KV.get(event.user)
-				console.log(`fetched at ${Date.now})
+				console.log(`fetched at ${Date.now}`)
 				return userData
 		})
+
+		// ✅ Good: steps that are dynamically named are constructed in a deterministic way.
+		// In this case, `catList` is a step output, which is stable, and `catList` is
+		// traversed in a deterministic fashion (no shuffles or random accesses) so,
+		// it's fine to dynamically name steps (e.g: create a step per list entry).
+		let catList = await step.do("get cat list from KV", async () => {
+			return await env.KV.get("cat-list")
+		})
+		for(const cat of carList) {
+			await step.do(`get cat: ${cat}`, async () => {
+				return await env.KV.get(cat)
+			})
+		}
 ```