Add sets to 102-built-in-types.md (#5806)

* Update 120-real-time-data.md (#5782)

Added links to pages containing brief explanations on the topics listed here.

* fix: correct spelling from "Synatx" to "Syntax" (#5784)

* Update 102-built-in-types.md

---------

Co-authored-by: devgru-3-2 <95485002+devgru-3-2@users.noreply.github.com>
Co-authored-by: Danrley Senegalha Pires <dan.osp@outlook.com>

src/data/roadmaps/flutter/content/100-dart-basics/102-built-in-types.md

@@ -7,6 +7,7 @@ There are several built-in data types, including:
 - String: used to store text
 - bool: used to store true or false values
 - List: used to store ordered collections of objects
+- Sets: used to store unordered collection of unique items
 - Map: used to store unordered collections of key-value pairs
 
 Additionally, there are other complex data types like dynamic, var, and Object in Dart programming language which is used in Flutter.
@@ -15,3 +16,4 @@ Visit the following resources to learn more:
 
 - [Built-in types](https://dart.dev/guides/language/language-tour#built-in-types)
 - [Overview of Built-in Types](https://dart.dev/guides/language/coming-from/js-to-dart#built-in-types)
+- [Collections | Dart](https://dart.dev/language/collections)