docs: add a note about .git being ignored in docker_build contexts (#…

…5748)

internal/tiltfile/api/__init__.py

@@ -228,7 +228,7 @@ def docker_build(ref: str,
     dockerfile_contents: raw contents of the Dockerfile to use for this build.
     live_update: set of steps for updating a running container (see `Live Update documentation <live_update_reference.html>`_).
     match_in_env_vars: specifies that k8s objects can reference this image in their environment variables, and Tilt will handle those variables the same as it usually handles a k8s container spec's ``image`` s.
-    ignore: set of file patterns that will be ignored. Ignored files will not trigger builds and will not be included in images. Follows the `dockerignore syntax <https://docs.docker.com/engine/reference/builder/#dockerignore-file>`_. Patterns will be evaluated relative to the ``context`` parameter.
+    ignore: set of file patterns that will be ignored, in addition to ``.git`` directory that's `ignored by default <file_changes.html#where-ignores-come-from>`_. Ignored files will not trigger builds and will not be included in images. Follows the `dockerignore syntax <https://docs.docker.com/engine/reference/builder/#dockerignore-file>`_. Patterns will be evaluated relative to the ``context`` parameter.
     only: set of file paths that should be considered for the build. All other changes will not trigger a build and will not be included in images. Inverse of ignore parameter. Only accepts real paths, not file globs. Patterns will be evaluated relative to the ``context`` parameter.
     entrypoint: command to run when this container starts. Takes precedence over the container's ``CMD`` or ``ENTRYPOINT``, and over a `container command specified in k8s YAML <https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/>`_. If specified as a string, will be evaluated in a shell context (e.g. ``entrypoint="foo.sh bar"`` will be executed in the container as ``/bin/sh -c 'foo.sh bar'``); if specifed as a list, will be passed to the operating system as program name and args.
     target: Specify a build stage in the Dockerfile. Equivalent to the ``docker build --target`` flag.