(docs) update README with more instructions.

Author: christianarty

README.md

@@ -91,6 +91,8 @@ Follow the [installation guide](https://github.com/ankitpokhrel/jira-cli/wiki/In
    more [here](https://github.com/ankitpokhrel/jira-cli/discussions/356).
 2. Run `jira init`, select installation type as `Cloud`, and provide required details to generate a config file required
    for the tool.
+3. Run the `jira init`, Select  the `Cloud` installation type and then select the `OAuth` authentication type. This will prompt for your Jira App Client ID and Client Secret. You can learn more about how to create a Jira App [here](link-to-a-discussion)
+
 
 #### On-premise installation
 
@@ -117,12 +119,13 @@ See [FAQs](https://github.com/ankitpokhrel/jira-cli/discussions/categories/faqs)
 
 #### Authentication types
 
-The tool supports `basic`, `bearer` (Personal Access Token), and `mtls` (Client Certificates) authentication types. Basic auth is used by
+The tool supports `basic`, `bearer` (Personal Access Token), `mtls` (Client Certificates), and `oauth` (OAuth 3LO) authentication types. Basic auth is used by
 default.
 
 - If you want to use PAT, you need to set `JIRA_AUTH_TYPE` as `bearer`.
 - If you want to use `mtls` run `jira init`. Select installation type `Local`, and then select authentication type as `mtls`.
   - In case `JIRA_API_TOKEN` variable is set it will be used together with `mtls`.
+- If you want to use `oauth` run `jira init`. Select installation type `Cloud`, and then select authentication type as `oauth`. 
 
 #### Shell completion
 
@@ -850,7 +853,7 @@ Sprint 1:   3
 
 - https://jira.atlassian.com/browse/ECO-283
 - https://community.developer.atlassian.com/t/oauth-2-0-with-proof-key-for-code-exchange-pkce/80173/3
-- The 3LO doesn't support PKCE, to avoid the need for a client secret, so we need to use the legacy auth flow.
+- The 3LO doesn't support [Proof Key for Code Exchange (PKCE)](https://oauth.net/2/pkce/). Without this support, we would have to share the single distrubuted app's client secret with all the consumers. To avoid the need for globally sharing a client secret, each consumer will need to create a JIRA app to effectively use as a proxy into your Jira cloud instance. 
 
 ## Feature requests