Add README for cmd/samples/recipes/branch

Signed-off-by: Diana Zawadzki <[email protected]>

Author: zawadzkidiana

cmd/samples/recipes/branch/README.md

@@ -0,0 +1,108 @@
+# Branch Sample
+
+This sample demonstrates **parallel execution** - running multiple activities concurrently using two different approaches.
+
+> **Looking for a visual guide?** See [new_samples/hello_world](../../../../new_samples/hello_world/) for a step-by-step tutorial with screenshots.
+
+## Two Approaches to Parallelism
+
+### 1. Futures (`-c branch`)
+Execute activities in parallel, collect futures, then wait for all:
+
+```
+     ┌─────────────┐
+     │   Start     │
+     └──────┬──────┘
+   ┌────────┼────────┐
+   ▼        ▼        ▼
+┌─────┐  ┌─────┐  ┌─────┐
+│ A1  │  │ A2  │  │ A3  │   (parallel)
+└──┬──┘  └──┬──┘  └──┬──┘
+   └────────┼────────┘
+            ▼
+     ┌─────────────┐
+     │ Wait all    │
+     └─────────────┘
+```
+
+### 2. Coroutines (`workflow.Go`)
+Spawn goroutine-like coroutines with channels for coordination:
+
+```
+     ┌─────────────┐
+     │   Start     │
+     └──────┬──────┘
+        ┌───┴───┐
+        ▼       ▼
+   ┌─────────┐ ┌─────┐
+   │ A1 → A2 │ │ A3  │   (parallel branches)
+   └────┬────┘ └──┬──┘
+        └────┬────┘
+             ▼
+     ┌─────────────┐
+     │ channel.Receive │
+     └─────────────┘
+```
+
+## Prerequisites
+
+1. Cadence server running (see [main README](../../../../README.md))
+2. Build the samples: `make`
+
+## Running the Sample
+
+```bash
+# Terminal 1: Start worker
+./bin/branch -m worker
+
+# Terminal 2: Trigger workflows
+./bin/branch -m trigger              # Coroutines approach (default)
+./bin/branch -m trigger -c branch    # Futures approach
+```
+
+## Key Code
+
+### Futures Pattern
+```go
+var futures []workflow.Future
+for i := 1; i <= totalBranches; i++ {
+    future := workflow.ExecuteActivity(ctx, sampleActivity, input)
+    futures = append(futures, future)
+}
+// Wait for all
+for _, future := range futures {
+    future.Get(ctx, nil)
+}
+```
+
+### Coroutines Pattern
+```go
+waitChannel := workflow.NewChannel(ctx)
+
+workflow.Go(ctx, func(ctx workflow.Context) {
+    workflow.ExecuteActivity(ctx, activity1).Get(ctx, nil)
+    workflow.ExecuteActivity(ctx, activity2).Get(ctx, nil)
+    waitChannel.Send(ctx, "done")
+})
+
+workflow.Go(ctx, func(ctx workflow.Context) {
+    workflow.ExecuteActivity(ctx, activity3).Get(ctx, nil)
+    waitChannel.Send(ctx, "done")
+})
+
+// Wait for both coroutines
+waitChannel.Receive(ctx, nil)
+waitChannel.Receive(ctx, nil)
+```
+
+## Testing
+
+```bash
+go test -v ./cmd/samples/recipes/branch/
+```
+
+## References
+
+- [Parallel Execution](https://cadenceworkflow.io/docs/go-client/execute-activity/)
+- [Workflow Coroutines](https://cadenceworkflow.io/docs/go-client/workflow-patterns/)
+