Exercise: count characters - sort by frequency

---

• Given a string count how many time each character appears and list them by frequency.
• Make the count case-insensitive (so "T" and "t" will count as the same letter.)

examples/count-characters-by-frequency-skeleton/count_characters_by_frequency_skeleton.go

package main

import (
    "fmt"
)

func main() {
    text := "This is a very long text. OK, maybe it is not that long after all."
    fmt.Println(text)

}

Expected output:

This is a very long text. OK, maybe it is not that long after all.
s: 3
r: 2
l: 4
n: 3
x: 1
.: 2
m: 1
h: 2
b: 1
v: 1
t: 7
T: 1
e: 4
o: 3
O: 1
K: 1
,: 1
a: 5
y: 2
g: 2
f: 1
i: 4