docs(divide): add description of subject

subjects/devops/division/README.md

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+## division
+
+### Instructions
+
+In this exercise, you will make a script `division.sh` that will take two arguments from the command line, and divide the first one by the second one.
+
+You will need to handle what to do when the inputs are wrong.
+
+If the divisor is `0` you will need to output `Error: division by zero is not allowed`.
+
+If the arguments are not numbers, the output should be `Error: both arguments must be numeric`.
+
+In the case where the number of arguments are not enough, the output should be `Error: two numbers should be provided`.
+
+Your script should handle very large numbers as well.
+
+For this exercise the use of the `test` command is not allowed.
+
+### Usage
+
+```console
+$ ./divide.sh 4 1
+4
+$
+```
+
+### Hints
+
+You can use the following to help you solve this exercise:
+
+[Bash conditional construct](https://www.gnu.org/software/bash/manual/bash.html#Conditional-Constructs) can be used to decide whether to execute a specific command. Below an example `script.sh`.
+
+```bash
+#!/usr/bin/env bash
+if [[ 1 > 2 ]]; then
+    echo "true"
+else
+    echo "false"
+fi
+```
+
+And its output:
+
+```console
+$ bash script.sh
+false
+```
+
+It is possible to combine several conditions with the **AND** (`&&`) and **OR** (`||`) logical operators. Below and example `script.sh`.
+
+```bash
+if [[ 1 > 2 ]] || [[ 1 == 1 ]]; then
+    echo "true"
+else
+    echo "false"
+fi
+if [[ 1 > 2 ]] && [[ 1 == 1 ]]; then
+    echo "true"
+else
+    echo "false"
+fi
+```
+
+And its output:
+
+```console
+true
+false
+```
+
+[bc](https://www.gnu.org/software/bc/manual/html_mono/bc.html) is a Unix utility that performs arbitrary precision arithmetic. It is particularly useful to handle numbers that are too large. One way of using it is as below:
+
+```console
+$ echo "2 + 2" | bc
+4
+$
+```