pxt-microbit Accessibility PR (#529)

* Accessibility changes

docs/projects/plant-watering.md

@@ -1,19 +1,19 @@
 # Plant Watering
 
 
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 Water your plants automatically!
 
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 https://youtu.be/7eC_VjH1eP0
 
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 This is a follow up of the **[soil moisture project](/projects/soil-moisture)**.
 
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 ## Materials
 
@@ -32,8 +32,8 @@ This is a follow up of the **[soil moisture project](/projects/soil-moisture)**.
 * [Make](/projects/plant-watering/make)  
 * [Code](/projects/plant-watering/code)
 
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 Let's get started!
 
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