doc: documentating every helpers of "it" sub-package

docs/data/it-chunkstring.md

@@ -0,0 +1,45 @@
+---
+name: ChunkString
+slug: chunkstring
+sourceRef: it/string.go#L130
+category: it
+subCategory: string
+playUrl: ""
+variantHelpers:
+  - it#string#chunkstring
+similarHelpers:
+  - core#string#chunkstring
+position: 0
+signatures:
+  - "func ChunkString[T ~string](str T, size int) iter.Seq[T]"
+---
+
+Returns a sequence of chunks of length `size` from the input string. If the string length is not a multiple of `size`, the final chunk contains the remaining characters. Panics if `size <= 0`.
+
+Examples:
+
+```go
+// Even split
+seq := it.ChunkString("123456", 2)
+var out []string
+for s := range seq { out = append(out, s) }
+// out == []string{"12", "34", "56"}
+```
+
+```go
+// Remainder chunk
+seq := it.ChunkString("1234567", 2)
+var out []string
+for s := range seq { out = append(out, s) }
+// out == []string{"12", "34", "56", "7"}
+```
+
+```go
+// Empty and small inputs
+seq1 := it.ChunkString("", 2)
+seq2 := it.ChunkString("1", 2)
+// seq1 yields ""
+// seq2 yields "1"
+```
+
+