doc: move SumBy

README.md

@@ -99,6 +99,7 @@ Supported math helpers:
 
 - Range / RangeFrom / RangeWithSteps
 - Clamp
+- SumBy
 
 Supported helpers for strings:
 
@@ -141,7 +142,6 @@ Supported search helpers:
 - Nth
 - Sample
 - Samples
-- SumBy
 
 Other functional programming helpers:
 
@@ -840,6 +840,19 @@ r3 := lo.Clamp(42, -10, 10)
 // 10
 ```
 
+### SumBy 
+
+Summarizes the values in a collection using the given return value from the iteration function.
+If collection is empty 0 is returned.
+
+```go
+strings := []string{"foo", "bar"}
+sum := lo.SumBy(strings, func(item string) int {
+    return len(item)
+})
+// 6
+```
+
 ### Substring
 
 Return part of a string.
@@ -1191,19 +1204,6 @@ lo.Samples[string]([]string{"a", "b", "c"}, 3)
 // []string{"a", "b", "c"} in random order
 ```
 
-### SumBy 
-
-Summarizes the values in a collection using the given return value from the iteration function.
-If collection is empty 0 is returned.
-
-```go
-strings := []string{"foo", "bar"}
-sum := lo.SumBy(strings, func(item string) int {
-    return len(item)
-})
-// 6
-```
-
 ### Ternary
 
 A 1 line if/else statement.