Update README.md to use stable branch on readthedocs (#571)

README.md

@@ -7,7 +7,7 @@
 ### Quick Links
 
 [Website](https://cornac.preferred.ai/) |
-[Documentation](https://cornac.readthedocs.io/en/latest/index.html) |
+[Documentation](https://cornac.readthedocs.io/en/stable/index.html) |
 [Tutorials](tutorials#tutorials) |
 [Examples](https://github.com/PreferredAI/cornac/tree/master/examples#cornac-examples-directory) |
 [Models](#models) |
@@ -19,7 +19,7 @@
 [![CircleCI](https://img.shields.io/circleci/project/github/PreferredAI/cornac/master.svg?logo=circleci)](https://circleci.com/gh/PreferredAI/cornac)
 [![AppVeyor](https://ci.appveyor.com/api/projects/status/0yq4td1xg4kkhdwu?svg=true)](https://ci.appveyor.com/project/tqtg/cornac)
 [![Codecov](https://img.shields.io/codecov/c/github/PreferredAI/cornac/master.svg?logo=codecov)](https://codecov.io/gh/PreferredAI/cornac)
-[![Docs](https://img.shields.io/readthedocs/cornac/latest.svg)](https://cornac.readthedocs.io/en/latest)
+[![Docs](https://img.shields.io/readthedocs/cornac/latest.svg)](https://cornac.readthedocs.io/en/stable)
 <br />
 [![Release](https://img.shields.io/github/release-pre/PreferredAI/cornac.svg)](https://github.com/PreferredAI/cornac/releases)
 [![PyPI](https://img.shields.io/pypi/v/cornac.svg)](https://pypi.org/project/cornac/)
@@ -126,7 +126,7 @@ $ curl -X GET "http://localhost:8080/recommend?uid=63&k=5&remove_seen=false"
 
 # Response: {"recommendations": ["50", "181", "100", "258", "286"], "query": {"uid": "63", "k": 5, "remove_seen": false}}
 ```
-If we want to remove seen items during training, we need to provide `TRAIN_SET` which has been saved with the model earlier, when starting the serving app. We can also leverage [WSGI](https://flask.palletsprojects.com/en/3.0.x/deploying/) server for model deployment in production. Please refer to [this](https://cornac.readthedocs.io/en/latest/user/iamadeveloper.html#running-an-api-service) guide for more details.
+If we want to remove seen items during training, we need to provide `TRAIN_SET` which has been saved with the model earlier, when starting the serving app. We can also leverage [WSGI](https://flask.palletsprojects.com/en/3.0.x/deploying/) server for model deployment in production. Please refer to [this](https://cornac.readthedocs.io/en/stable/user/iamadeveloper.html#running-an-api-service) guide for more details.
 
 ## Efficient retrieval with ANN search
 
@@ -202,7 +202,7 @@ The recommender models supported by Cornac are listed below. Why don't you join
 
 ## Contributing
 
-This project welcomes contributions and suggestions. Before contributing, please see our [contribution guidelines](https://cornac.readthedocs.io/en/latest/developer/index.html).
+This project welcomes contributions and suggestions. Before contributing, please see our [contribution guidelines](https://cornac.readthedocs.io/en/stable/developer/index.html).
 
 ## Citation