Added README.md documentation for CPU only installations (#365)

* changed README.md to reflect installation options.

* added setup script to demonstrate how wrapper could look for CPU installations

* removed setup.sh as unnessescary for cpu only builds

* Initial commit for merge_cdb method

* Added indentation to make merge_cdb a class method

* fixed syntax issues

* more lint fixes

* more lint fixes

* bug fixes of merge_cdb

* removed print statements

* Added commentary on disk space usage of pytorch-gpu

* removed merge_cdb from branch

---------

Co-authored-by: adam-sutton-1992 <[email protected]>

Author: adam-sutton-1992

README.md

@@ -38,6 +38,17 @@ To download any of these models, please [follow this link](https://uts.nlm.nih.g
 - **Paper**: [What’s in a Summary? Laying the Groundwork for Advances in Hospital-Course Summarization](https://www.aclweb.org/anthology/2021.naacl-main.382.pdf)
 - ([more...](https://github.com/CogStack/MedCAT/blob/master/media/news.md))
 
+## Installation
+To install the latest version of MedCAT run the following command:
+```
+pip install medcat
+```
+Normal installations of MedCAT will install torch-gpu and all relevant dependancies (such as CUDA). This can require as much as 10 GB more disk space, which isn't required for CPU only usage.
+
+To install the latest version of MedCAT without torch GPU support run the following command:
+```
+pip install medcat --extra_index_url https://download.pytorch.org/whl/cpu/
+```
 ## Demo
 A demo application is available at [MedCAT](https://medcat.rosalind.kcl.ac.uk). This was trained on MIMIC-III and all of SNOMED-CT.
 PS: This link can take a long time to load the first time around. The machine spins up as needed and spins down when inactive.