Add dev notes about how to connect to codespace using JetBrains products

Author: OptimumCode

README.md

@@ -356,6 +356,8 @@ The extension that is available for VS Code to support Kotlin works quite slow (
 and sometimes does not work correctly with multiplatform definitions.
 Because of that I higly recoment using JetBrains Gateway
 (but it looks like the GitHub Codespace provider is not currently compatible with latest Gateway version).
+However, there is a way to connect to Codespace and work with project using JetBrains IDE.
+Please, read details [here](docs/codespaces_for_jetbrains.md).
 
 ## Future plans
 

docs/codespaces_for_jetbrains.md

@@ -0,0 +1,25 @@
+# Connect to Codespaces using JetBrains IDE
+
+## Pre-requirements
+
+1. You need to have [gh CLI](https://cli.github.com/) installed.
+2. JetBrains IDE that can connect to remote host via SSH
+
+## Steps
+
+1. Create Codespace in GitHub. You can do it either via the UI or using gh CLI.
+2. Create local SSH server that is connected to the Codespace you need.
+  ```bash
+  gh cs ssh --server-port <port>
+  ```
+  For example,
+  ```bash
+  gh cs ssh --server-port 30042
+  ```
+  You will see something like this:
+  ```text
+  $ gh cs ssh --server-port 30042
+  ? Choose codespace: OptimumCode/json-schema-validator (main): redesigned zebra
+  Connection Details: ssh vscode@localhost [-p 30042 -o NoHostAuthenticationForLocalhost=yes -o PasswordAuthentication=no]
+  ```
+3. Connect to Codespace using the displayed connection details.