Minor text change to Download Data button

## I'm submitting a ...
Check one of the following options with "x" and add the appropriate label to the issue as well

[X] Bug report 

[ ] Regression (behaviour that used to work and stopped working in a new release)

**Describe the Issue**
The Download Data button should be amended to Download data for consistency with the Share button.

Sorry, very minor - but thought best to raise here on GH. Hope you won't mind me skipping the further details below, seems like overkill...

**To Reproduce**
Replace the content below with the steps to reproduce the behaviour.
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

**Expected Behaviour**
A clear and concise description of what you expected to happen

**Screenshots/GIF**
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**Desktop (please complete the following information):**
- OS: [e.g. iOS]
- Browser [e.g. chrome, safari]
- Version [e.g. 22]

**Smartphone (please complete the following information):**
- Device: [e.g. iPhone6]
- OS: [e.g. iOS8.1]
- Browser [e.g. stock browser, safari]
- Version [e.g. 22]

**Environment/Server:**

- [ ] Production

- [ ] Staging

- [ ] Test

- [ ] Development

**Additional Context**
Add any other context about the problem here.

Requested Delivery Date: dd/MMM/YYYY