Added subtitles and context

Author: rijulshrestha

sites/cheerpj/src/content/docs/11-guides/library-mode.md

@@ -5,8 +5,15 @@ description: Use Java libraries in JavaScript
 
 Library mode allows you to directly use Java methods, objects, and arrays from JavaScript. This API has been designed to take advantage of async/await to feel more natural to use, without sacrificing any flexibility.
 
+# Getting started
+
 Loading a library is as simple as calling [`cheerpjRunLibrary`].
 
+- `await cheerpjRunLibrary("")` loads **only the Java standard library**
+- `await cheerpjRunLibrary("/path/to/some.jar")` loads the Java standard library **plus** that JAR
+
+An example of using the standard Java library.
+
 ```js
 async function libraryModeTour() {
 	await cheerpjInit();
@@ -54,7 +61,15 @@ async function libraryModeTour() {
 }
 ```
 
-Library mode can be used to integrate powerful Java libraries into your Web application. As a practical example, these few lines of code make it possible to generate a PDF from JavaScript using the popular iText library:
+# Example: generating a PDF with iText
+
+Library mode can be used to integrate powerful Java libraries into your Web application. As a practical example, these few lines of code make it possible to generate a PDF from JavaScript using the popular iText library.
+
+**This example:**
+
+- Loads `itextpdf-5.5.13.3.jar`
+- Builds a PDF and writes it to `/files/HelloIText.pdf`
+- Reads it back as a blob and shows it in the page
 
 ```js
 async function iTextExample() {
@@ -91,7 +106,7 @@ async function iTextExample() {
 }
 ```
 
-## See also
+# See also
 
 Library mode is also used for [native methods implemented in JavaScript][JNI]. A `native` is effectively just a shorter library mode session.