Doc for using vanilla gpt (#90)

* Create ChatGPT using OpenAI APIs

Basic documentation (without pictures)

* Update ChatGPT using OpenAI APIs

Added links

* Update and rename ChatGPT using OpenAI APIs to ChatGPT using OpenAI APIs.md

Added images and formatting

* Update ChatGPT using OpenAI APIs.md

Added pictures and additional formatting

* Update ChatGPT using OpenAI APIs.md

added ending tag "/>" for images to resolve the issue in deployment

docs/4. Integrations/ChatGPT using OpenAI APIs.md

@@ -0,0 +1,64 @@
+> ###**3 minute read                                                                                                                         `Advanced`**
+
+## Using ChatGPT within Glific using the OpenAI APIs
+
+_**Leverage the capabilities of GPT models developed by OpenAI by using OpenAI APIs.**_
+
+## Pre-requisites 
+1. Create an account in OpenAI platform [platform](https://openai.com/product) 
+2. Create new API keys
+3. Make sure there is enough credit in OpenAI account to allow usage.
+4. Pricing for API calls is as per OpenAI platform [pricing](https://openai.com/pricing)
+
+<img width="1060" alt="Screenshot 2024-02-07 at 10 50 58 AM" src="https://github.com/glific/docs/assets/141305477/d3c22780-a4ae-4aaa-b196-1d079fce7eb5" />
+
+_Above is a representative image from the OpenAI platform account_
+
+## How it will work 
+
+1. Question is asked by the user after the flow is initiated
+2. OpenAI API call is made using webhooks within the flow
+3. Model being called to generate responses is `gpt-3.5-turbo-16k`
+4. The response to the question is then sent to the user
+
+## Steps to follow to set up OpenAI API in Glific platform
+1. Go to `Settings`, find `OpenAI (ChatGPT) (Beta)`
+2. Click on `is active` and paste the OpenAI API key from your OpenAI platform account
+
+<img width="591" alt="Screenshot 2024-02-07 at 10 48 51 AM" src="https://github.com/glific/docs/assets/141305477/87adef8e-1858-4aa6-8b46-7f976cfbb9fb" />
+
+## Using the webhook for OpenAI API call in a Glific flow
+
+<img width="1069" alt="Screenshot 2024-02-07 at 9 59 24 AM" src="https://github.com/glific/docs/assets/141305477/babb9e27-fce5-4b2b-81d9-58017fd1a079" />
+
+_Representative image to explain the steps in OpenAI API calls in a simple flow_
+
+[Sample flow](https://drive.google.com/file/d/1jl0NWn73YlK1qMRedaPnGCQwDKHfG_7j/view?usp=drive_link)
+
+
+1. Get the user question 
+2. In `call a webhook` node, select `function` and paste function name as `parse_via_chat_gpt`
+
+  <img width="684" alt="Screenshot 2024-02-07 at 10 52 49 AM" src="https://github.com/glific/docs/assets/141305477/f1165b6b-483c-43b4-9e8d-7bb6044d6e24" />
+
+3. Share the following function body 
+ ` {
+  "contact": "@contact",
+  "results": "@results",
+  "question_text": "@results.question" 
+  }`
+
+here `question_text` is the parameter name corresponding to user question. 
+
+<img width="711" alt="Screenshot 2024-02-07 at 10 53 21 AM" src="https://github.com/glific/docs/assets/141305477/65622c0e-2dfb-41fb-8f6d-a836e8a0f81d" />
+
+4. The response from GPT is shown as `@results.webhookresultname.parsed_msg`, in the given example `gpt_response` is the webhook result name. 
+
+
+## Limitations 
+1. At present, this is simple question answer with the GPT model `gpt-3.5-turbo-16k`
+2. Selection of GPT model is not yet customizable from org Glific instances
+3. Additional system prompt is not yet customizable from org Glific instances
+4. Parameters like temperature, top P etc are not yet customizable from org Glific instances
+
+_Reach out to the Glific team to flag any further customizations within this functionality_