[Term Entry] Swift Arrays: capacity #6969 (#6991)

* create term entry Capacity

* add more ditails to the entry

* Remove extra strings

* Remove extra edits (in term-entry-template.md)

* minor content fixes

* fixed format

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Author: grig-v

content/swift/concepts/arrays/terms/capacity/capacity.md

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+---
+Title: 'Capacity'
+Description: 'Returns the total number of elements that the array can contain without allocating new storage.'
+Subjects:
+  - 'Computer Science'
+  - 'IOS'
+  - 'Mobile Development'
+Tags:
+  - 'Arrays'
+  - 'Collections'
+  - 'Data Structures'
+  - 'Memory'
+  - 'Swift'
+  - 'Variables'
+CatalogContent:
+  - 'learn-swift'
+  - 'paths/build-ios-apps-with-swiftui'
+---
+
+The **`capacity`** of a Swift [array](https://www.codecademy.com/resources/docs/swift/arrays) represents the amount of memory currently allocated to store elements without requiring a resize. If the number of elements exceeds this capacity, the array automatically reallocates memory, usually following an exponential growth pattern—to ensure efficient performance during appends.
+
+## Syntax
+
+```pseudo
+array.capacity
+```
+
+**Parameters:**
+
+`capacity` is a read-only property and does not take any parameters.
+
+**Return value:**
+
+Returns the number of elements the array can store in its currently allocated memory without reallocating.
+
+## Example
+
+The following code prints the array's initial capacity, appends elements, and then prints the updated capacity to show how Swift manages memory allocation dynamically:
+
+```swift
+var numbers: [Int] = []
+print(numbers.capacity)
+
+numbers.append(1)
+numbers.append(2)
+numbers.append(3)
+print(numbers.capacity)
+```
+
+The output of this code will be:
+
+```shell
+0
+3
+```