Harrison/quick start (#12491)

Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>

templates/docs/LAUNCHING_PACKAGE.md

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+# Launching LangServe from a Package
+
+You can also launch LangServe directly from a package, without having to pull it into a project.
+This can be useful when you are developing a package and want to test it quickly.
+The downside of this is that it gives you a little less control over how the LangServe APIs are configured,
+which is why for proper projects we recommend creating a full project.
+
+In order to do this, first change your working directory to the package itself.
+For example, if you are currently in this `templates` module, you can go into the `pirate-speak` package with:
+
+```shell
+cd pirate-speak
+```
+
+Inside this package there is a `pyproject.toml` file.
+This file contains a `tool.langchain` section that contains information on how this package should be used.
+For example, in `pirate-speak` we see:
+
+```text
+[tool.langserve]
+export_module = "pirate_speak.chain"
+export_attr = "chain"
+```
+
+This information can be used to launch a LangServe instance automatically.
+In order to do this, first make sure the CLI is installed:
+
+```shell
+pip install -U "langchain-cli[serve]"
+```
+
+You can then run:
+
+```shell
+langchain hub start
+```
+
+This will spin up endpoints, documentation, and playground for this chain.
+For example, you can access the playground at [http://127.0.0.1:8000/playground/](http://127.0.0.1:8000/playground/)
+
+![playground.png](playground.png)