Dealing with deleted research folder and Tensorflow Object Detection API

Prerequisites

Please answer the following questions for yourself before submitting an issue.

• [] I am using the latest TensorFlow Model Garden release and TensorFlow 2.
• I am reporting the issue to the correct repository. (Model Garden official or research directory)
• I checked to make sure that this issue has not been filed already.

1. The entire URL of the file you are using

https://github.com/tensorflow/models/tree/master/official/...

2. Describe the bug

When using an older version of Tensorflow (v2.5.0), the research folder does not exist.
I don't understand how the instructions on this page https://tensorflow-object-detection-api-tutorial.readthedocs.io/en/latest/install.html#tensorflow-installation, which were designed for use with TF 2.5 ever worked since the research folder has been deleted for several versions before this.

3. Steps to reproduce

git clone -b v2.5.0 https://github.com/tensorflow/models.git

4. Expected behavior

Expected folder structure as specified precisely in the latest official documentation for the object detection API
https://tensorflow-object-detection-api-tutorial.readthedocs.io/en/latest/install.html#tensorflow-installation

TensorFlow/
└─ models/
   ├─ community/
   ├─ official/
   ├─ orbit/
   ├─ research/
   └── ...

However the ACTUAL folder structure is missing the research folder.

5. Additional context

N/A

6. System information

• OS Platform and Distribution = Linux
• TensorFlow installed from (source or binary): N/A
• TensorFlow version (use command below): 2.5
• Python version: 3.x
• Bazel version (if compiling from source): N/A
• GCC/Compiler version (if compiling from source): N/A
• CUDA/cuDNN version: N/A
• GPU model and memory: N/A