* Create doc tree index for Nano How-to Guides
* Add How to guide for PyTorch Inference using ONNXRuntime
* Add How to guide for PyTorch Inference using OpenVINO
* Update How to guide for PyTorch Inference using OpenVINO/ONNXRuntime
* Change current notebook to md and revise contents to be more concentrated
* Add How-to Guide: Install BigDL-Nano in Google Colab (need further update)
* Revise words in How-to Guide for PyTorch Inference using OpenVINO/ONNXRuntime
* Add How-To Guide: Quantize PyTorch Model for Inference using Intel Neural Compressor
* Add How-To Guide: Quantize PyTorch Model for Inference using Post-training Quantization Tools
* Add API doc links and small revision
* Test: syncronization through marks in py files
* Test: syncronization through notebook with cells hidden from rendering in doc
* Remove test commits for runnable example <-> guides synchronization
* Enable rendering notebook from location out of sphinx source root
* Update guide "How to accelerate a PyTorch inference pipeline through OpenVINO" to notebook under python folder
* Update guide "How to quantize your PyTorch model for inference using Intel Neural Compressor" to notebook under python folder
* Fix bug that markdown will be ignored inside html tags for nbconvert, and notebook revise
* Update guide 'How to quantize your PyTorch model for inference using Post-training Optimization Tools' to notebook under python folder
* Small updates to index and current guides
* Revision based on Junwei's comments
* Update how-to guides: How to install BigDL-Nano in Google Colab, and update index page
* Small typo fix
* Add extension nbsphinx-link: link notebook out of the sphinx root folder to the sphinx project
* Link Notebook custom.ipynb directly from python folder to the sphinx project
* Link Notebook seq_and_func.ipynb directly from python folder to the sphinx project
* Small title fix
* Make interactive graphs visible in readthedocs webpage for seq_and_func.ipynb
* Regenerate outputs for custom.ipynb and remove parts of them
* Add nbsphinx extension for docs
* Add specific ipynb files to readthedocs folder and add links to Nano Tutorials index page
* Disable execution of ipynb notebook
* Remove outputs of two ipynb files
* Rename titles and add navigation texts to seq_and_func.ipynb under readthedocs folder
* Rename titles and add navigation texts to custom.ipynb file under readthedocs folder
