Improve portal README.md formatting and clarity (#22173)

improving the portal readme file

Signed-off-by: rgcr <[email protected]>

Author: rgcr

src/portal/README.md

@@ -1,25 +1,50 @@
 ![Harbor UI](https://raw.githubusercontent.com/goharbor/website/master/docs/img/readme/harbor_logo.png)
 
-Harbor UI
-============
-This is the project based on Clarity and Angular to build Harbor UI.
+# Harbor UI
 
+This project is the web interface for [Harbor](https://goharbor.io), built using [Clarity Design System](https://clarity.design/) and Angular.
 
+## Getting Started
 
-Start
-============
-1. Use the specified Node version:
-Run the following command to use the Node version specified in the .nvmrc file:
-```bash
-nvm install   # Install the Node version specified in .nvmrc (if not already installed)
+### 1. Use the correct Node version
+
+To ensure compatibility with dependencies, use the Node version defined in `.nvmrc`.
+
+```
+nvm install   # Install the Node version from .nvmrc (if not already installed)
 nvm use       # Switch to the specified Node version
 ```
-This step helps avoid compatibility issues, especially with dependencies.
-2. npm install (should trigger 'npm postinstall')
-3. npm run postinstall  (if not triggered, manually run this step)
-4. copy "proxy.config.mjs.temp" file to "proxy.config.mjs"
-   `cp proxy.config.mjs.temp proxy.config.mjs`
-5. Modify "proxy.config.mjs" to specify a Harbor server. And you can specify the agent if you work behind a corporate proxy
-6. npm run start
-7. open your browser on https://localhost:4200
+
+### 2. Install dependencies
+
+```
+npm install
+```
+
+> Note: `npm install` should automatically trigger the `postinstall` script.
+If `postinstall` scripts were not triggered, then run manually:  `npm run postinstall`
+
+
+### 3. Copy the template proxy file
+
+```
+cp proxy.config.mjs.temp proxy.config.mjs
+```
+
+### 4. Configure the proxy
+
+Edit `proxy.config.mjs` to specify the Harbor server.
+You can specify the agent if you work behind a corporate proxy.
+
+### 5. Start the development server
+
+```
+npm run start
+```
+
+### 6. Open the application
+
+Open your browser at https://localhost:4200
+
+