Created new article Cascading Select Multiple

[Kalyan-Lama]

@joshuaberetta, I have created a PR for a new article. Could you kindly review and merge it with the master branch? Thank you!

[joshuaberetta]

@Kalyan-Lama, sorry for the major delay in reviewing this! I started to make some edits but then saw that there's a simpler way to create this form that's easier to understand, based on the example I once made here in the forum. Could you please update the article with the following XLSForm — either to replace the one you've used or as an example of an alternative way of achieving the same outcome.

## survey

| type               | name | label                               | choice_filter        | relevant    | required |
| ------------------ | ---- | ----------------------------------- | -------------------- | ---         | ---      |
| select_multiple Q1 | Q1   | Q1. Select all that applies from Q1 |                      |             | true     |
| select_multiple Q2 | Q2   | Q2. Select all that applies from Q2 | contains(${Q1}, ref) | ${Q1} != '' | true     |

## choices

| list_name | name | label           | ref |
| --------- | ---- | --------------- | --- |
| Q1        | 1    | Choice 1 for Q1 |     |
| Q1        | 2    | Choice 2 for Q1 |     |
| Q1        | 3    | Choice 3 for Q1 |     |
| Q2        | 1    | Choice 1 for Q2 | 1   |
| Q2        | 2    | Choice 2 for Q2 | 1   |
| Q2        | 3    | Choice 3 for Q2 | 2   |
| Q2        | 4    | Choice 4 for Q2 | 2   |
| Q2        | 5    | Choice 5 for Q2 | 3   |
| Q2        | 6    | Choice 6 for Q2 | 3   |

## settings

| form_title                           |
| ------------------------------------ |
| Cascading a Select Multiple Question |

cascading-select-multiple.xlsx