update README.md

Author: galactixx

README.md

@@ -23,6 +23,16 @@ This library offers robust string wrapping capabilities with a focus on accurate
     * An indication of whether the line ended due to a hard break or soft wrapping.
     * A flag indicating if the segment ends with a word that was split during wrapping.
 
+## 💡 **Why Grapheme Clusters Matter**
+
+Both `StringWrap` and `StringWrapSplit` use Unicode grapheme cluster parsing (via the `uniseg` library) rather than simple rune iteration. This is crucial for accurate width calculation with complex Unicode sequences:
+
+* **ZWJ Emojis:** Sequences like "👩‍💻" (woman technologist) contain multiple runes but display as a single character
+* **Combining Marks:** Characters like "é" (e + combining acute accent) must be treated as one unit
+* **Full-width Characters:** Asian characters and emojis that occupy two columns
+
+While this approach is slower than rune-based processing, it prevents incorrect wrapping that would occur with naive rune counting. For applications requiring precise visual alignment (terminals, editors, formatted output), this accuracy is essential.
+
 ## 🚀 **Getting Started**
 
 ```bash