docs: update HELP.md for multi-template repository

  - Add documentation for both Kotlin Spring and Go Gin templates
  - Include template selection guide (sparse checkout)
  - Add Go-specific workflows (go.mod, gazelle, bazel mod tidy)
  - Update prerequisites and troubleshooting sections
  - Reorganize content for better readability

Author: kangeunchan

HELP.md

@@ -1,11 +1,67 @@
 # Help
 
-## Prerequisites
+## Available Templates
 
-- [Bazelisk](https://github.com/bazelbuild/bazelisk) (recommended) or Bazel 7.0+
-- JDK 17 or higher
+This repository contains multiple Bazel project templates:
 
-## Creating a New Module
+- **Kotlin Spring** (`kotlin/spring/`) - Multi-module Spring Boot template
+- **Go Gin** (`go/gin/`) - Single-module Gin web framework template
+
+Each template is an independent Bazel workspace with its own `MODULE.bazel`.
+
+## Using a Template
+
+### Option 1: Clone Specific Template (Recommended)
+
+Using Git sparse checkout to get only the template you need:
+
+```bash
+# Clone with sparse checkout
+git clone --filter=blob:none --sparse https://github.com/EntryDSM/entrydsm-bazel-template
+cd entrydsm-bazel-template
+
+# Checkout Kotlin Spring template
+git sparse-checkout set kotlin/spring
+
+# OR checkout Go Gin template
+git sparse-checkout set go/gin
+```
+
+### Option 2: Copy Template Directory
+
+```bash
+# Clone entire repository
+git clone https://github.com/EntryDSM/entrydsm-bazel-template
+
+# Copy the template you want
+cp -r entrydsm-bazel-template/kotlin/spring my-project
+# OR
+cp -r entrydsm-bazel-template/go/gin my-project
+
+cd my-project
+```
+
+---
+
+## Kotlin Spring Template
+
+### Prerequisites
+
+- [Bazelisk](https://github.com/bazelbuild/bazelisk) (recommended) or Bazel 8.5+
+- JDK 21 or higher
+
+### Project Structure
+
+```
+kotlin/spring/
+├── MODULE.bazel        # Bazel module definition
+├── BUILD.bazel         # Root build file
+├── kotlin.bzl          # Kotlin compiler configuration
+├── module-a/           # Example module
+└── module-b/           # Example module
+```
+
+### Creating a New Module
 
 1. Create the module directory structure:
 ```bash
@@ -14,7 +70,7 @@ mkdir -p module-name/src/test/kotlin
 ```
 
 2. Create `module-name/deps.bzl`:
-```bzl
+```starlark
 MODULE_DEPS = [
     "@maven//:org_springframework_boot_spring_boot_starter_web",
 ]
@@ -25,7 +81,7 @@ TEST_DEPS = [
 ```
 
 3. Create `module-name/BUILD.bazel`:
-```bzl
+```starlark
 load("@rules_kotlin//kotlin:jvm.bzl", "kt_jvm_binary", "kt_jvm_test")
 load("//:kotlin.bzl", "setup_kotlin_compiler", "setup_spring_allopen_plugin")
 load("//module-name:deps.bzl", "MODULE_DEPS", "TEST_DEPS")
@@ -56,27 +112,29 @@ kt_jvm_test(
 )
 ```
 
-## Adding Dependencies
+### Adding Maven Dependencies
 
-1. Add the Maven artifact to `MODULE.bazel`:
-```bzl
+1. Add the artifact to `MODULE.bazel`:
+```starlark
 maven.artifact(
     artifact = "artifact-name",
     group = "group.id",
     version = VERSION_CONSTANT,
 )
 ```
 
-2. Add the dependency to your module's `deps.bzl`:
-```bzl
+2. Add to your module's `deps.bzl`:
+```starlark
 MODULE_DEPS = [
     "@maven//:group_id_artifact_name",
 ]
 ```
 
-## Building and Testing
+### Building and Testing
 
 ```bash
+cd kotlin/spring
+
 # Build all targets
 bazel build //...
 
@@ -87,8 +145,174 @@ bazel test //...
 bazel run //module-name:main
 ```
 
+---
+
+## Go Gin Template
+
+### Prerequisites
+
+- [Bazelisk](https://github.com/bazelbuild/bazelisk) (recommended) or Bazel 8.5+
+- Go 1.25+ (optional, Bazel will download)
+
+### Project Structure
+
+```
+go/gin/
+├── MODULE.bazel        # Bazel module definition
+├── BUILD.bazel         # Gazelle configuration
+├── go.mod              # Go module (dependency source of truth)
+├── go.sum              # Go checksums
+└── cmd/
+    └── server/         # Server binary
+        ├── main.go
+        └── main_test.go
+```
+
+### Adding Go Dependencies
+
+1. Add dependency using Go tools:
+```bash
+cd go/gin
+go get github.com/some/package@version
+```
+
+2. Update Bazel:
+```bash
+bazel mod tidy
+```
+
+The `go.mod` file is the single source of truth for dependencies.
+
+### Creating New Packages
+
+1. Create your Go files:
+```bash
+mkdir -p internal/mypackage
+# Write your .go files
+```
+
+2. Run Gazelle to generate BUILD files:
+```bash
+bazel run //:gazelle
+```
+
+### Building and Testing
+
+```bash
+cd go/gin
+
+# Update dependencies
+bazel mod tidy
+
+# Build all targets
+bazel build //...
+
+# Run all tests
+bazel test //...
+
+# Run the server
+bazel run //cmd/server
+```
+
+### Running the Server Locally
+
+```bash
+# Using Bazel
+bazel run //cmd/server
+
+# OR using Go directly
+go run cmd/server/main.go
+```
+
+The server will start on `http://localhost:8080` with:
+- `GET /health` - Health check endpoint
+
+---
+
+## Common Commands
+
+### Bazel
+
+```bash
+# Clean build cache
+bazel clean
+
+# Show build graph
+bazel query //...
+
+# Build with verbose output
+bazel build //... --verbose_failures
+
+# Run specific test
+bazel test //path/to:test_target
+```
+
+### Go-Specific (in go/gin/)
+
+```bash
+# Update go.mod and go.sum
+go mod tidy
+
+# Update Bazel BUILD files
+bazel run //:gazelle
+
+# Update dependencies in MODULE.bazel
+bazel mod tidy
+```
+
+### Kotlin-Specific (in kotlin/spring/)
+
+```bash
+# Format Kotlin code
+bazel run @kotlin_formatter//file
+
+# Run with JVM debug
+bazel run //module:main --jvmopt=-agentlib:jdwp=...
+```
+
+---
+
 ## Getting Help
 
 - [Bazel Documentation](https://bazel.build/docs)
 - [rules_kotlin Documentation](https://github.com/bazelbuild/rules_kotlin)
+- [rules_go Documentation](https://github.com/bazel-contrib/rules_go)
+- [Gazelle Documentation](https://github.com/bazel-contrib/bazel-gazelle)
 - [Issue Tracker](../../issues)
+
+---
+
+## Troubleshooting
+
+### "No such package" errors
+
+Run `bazel clean` and rebuild:
+```bash
+bazel clean
+bazel build //...
+```
+
+### Go dependency issues
+
+1. Update go.mod:
+```bash
+go mod tidy
+```
+
+2. Update Bazel:
+```bash
+bazel mod tidy
+```
+
+3. Rebuild:
+```bash
+bazel build //...
+```
+
+### Maven dependency not found (Kotlin)
+
+1. Check dependency is in `MODULE.bazel`
+2. Verify the Maven coordinate format:
+   - Group: `com.example` → `com_example`
+   - Artifact: `my-lib` → `my_lib`
+   - Full: `@maven//:com_example_my_lib`