docs: Update Flash docs for .flashignore deprecation and built-in ignore patterns (#588)

Author: muhsinking

flash/apps/build-app.mdx

@@ -55,7 +55,6 @@ This is the structure of the project template created by `flash init`:
     <Tree.File name="gpu_worker.py" />
     <Tree.File name="cpu_worker.py" />
     <Tree.File name=".env.example" />
-    <Tree.File name=".flashignore" />
     <Tree.File name=".gitignore" />
     <Tree.File name="pyproject.toml" />
     <Tree.File name="requirements.txt" />

flash/apps/deploy-apps.mdx

@@ -336,7 +336,7 @@ Each endpoint maintains its own connection to the state manager, querying for pe
 If the build process can't find your endpoint functions:
 
 - Ensure functions are decorated with `@Endpoint(...)`.
-- Check that Python files aren't excluded by `.gitignore` or `.flashignore`.
+- Check that Python files aren't excluded by `.gitignore` or Flash's [built-in ignore patterns](/flash/cli/build#built-in-ignore-patterns).
 - Verify decorator syntax is correct.
 
 ### Deployment size limit exceeded

flash/apps/initialize-project.mdx

@@ -41,7 +41,6 @@ uv run flash init .
     <Tree.File name="gpu_worker.py" />
     <Tree.File name="cpu_worker.py" />
     <Tree.File name=".env.example" />
-    <Tree.File name=".flashignore" />
     <Tree.File name=".gitignore" />
     <Tree.File name="pyproject.toml" />
     <Tree.File name="requirements.txt" />
@@ -57,8 +56,6 @@ uv run flash init .
 
 **cpu_worker.py**: An example CPU queue-based worker. Contains `@Endpoint` functions that run on CPU-only instances. Provides `/runsync` route for job submission. Creates one endpoint when deployed.
 
-**.flashignore**: Lists files and directories to exclude from the deployment artifact (similar to `.gitignore`).
-
 Each worker file defines a resource configuration and its associated functions. When you deploy, Flash creates one Serverless endpoint per unique resource configuration.
 
 ## Set up the project

flash/cli/build.mdx

@@ -52,6 +52,25 @@ Comma-separated list of packages to exclude from the build (e.g., `torch,torchvi
 5. **Dependency installation**: Installs Python packages for Linux x86_64.
 6. **Packaging**: Bundles everything into `.flash/artifact.tar.gz`.
 
+## Built-in ignore patterns
+
+Flash automatically excludes certain files and directories from deployment artifacts. These patterns cover common development files that shouldn't be deployed to production.
+
+| Category | Patterns |
+|----------|----------|
+| Build artifacts | `.build/`, `.flash/`, `.runpod/`, `*.tar.gz`, `.git/`, `__pycache__/`, `*.pyc`, `*.pyo`, `*.pyd`, `*.egg-info/`, `dist/`, `build/` |
+| Virtual environments | `.venv/`, `venv/`, `env/` |
+| IDE files | `.vscode/`, `.idea/` |
+| Environment files | `.env`, `.env.local` |
+| Tests | `tests/`, `test_*.py`, `*_test.py` |
+| Documentation | `docs/`, `*.md` (except `README.md`) |
+
+Flash also respects your `.gitignore` file and excludes any files matching those patterns.
+
+<Tip>
+If you use other environment file variants like `.env.dev` or `.env.staging`, add them to your `.gitignore` to exclude them from deployment artifacts.
+</Tip>
+
 ## Build artifacts
 
 After running `flash build`:

flash/cli/init.mdx

@@ -48,7 +48,6 @@ The command creates the following project structure:
     <Tree.File name="gpu_worker.py" />
     <Tree.File name="cpu_worker.py" />
     <Tree.File name=".env.example" />
-    <Tree.File name=".flashignore" />
     <Tree.File name=".gitignore" />
     <Tree.File name="pyproject.toml" />
     <Tree.File name="requirements.txt" />

flash/troubleshooting.mdx

@@ -244,7 +244,7 @@ Tarball exceeds maximum size. File size: 1.6GB, Max: 1.5GB
 **Solution:**
 
 1. Check for large files that shouldn't be included (datasets, model weights, logs).
-2. Add large files to `.flashignore` to exclude them from the build.
+2. Add large files to `.gitignore` to exclude them from the build.
 3. Use [network volumes](/flash/configuration/storage) to store large models instead of bundling them.
 
 ### Invalid tarball format