Update in-depth-guide.md reference

[emmanuel-ferdman]

PR Summary

Small PR - The tensorflow/tools/proto_splitter/in-depth-guide.md was moved to tensorflow/tools/proto_splitter/g3doc/in-depth-guide.md. This PR adjusts sources to changes. See here for more info: tensorflow/tensorflow@752a1ab

[github-actions]

Preview

Preview and run these notebook edits with Google Colab:

• site/en/guide/saved_model.ipynb

Rendered notebook diffs available on ReviewNB.com.

Format and style

Use the TensorFlow docs notebook tools to format for consistent source diffs and lint for style:

$ python3 -m pip install -U --user git+https://github.com/tensorflow/docs

$ python3 -m tensorflow_docs.tools.nbfmt notebook.ipynb

$ python3 -m tensorflow_docs.tools.nblint --arg=repo:tensorflow/docs notebook.ipynb

If commits are added to the pull request, synchronize your local branch: git pull origin master