Add missing alt text to image markup

Alternate text is important for accessibility and describes the content of an image for people who may not be able to
see it.

For this reason, the markdownlint tool is used to detect missing alternate text in the Markdown-based assets.

Author: per1234

content/categories/hardware/arduino-starter-kit/_topics/about-the-the-arduino-starter-kit/1.md

@@ -2,8 +2,8 @@ Quickly and easily get started with learning electronics using the Arduino Start
 
 https://store.arduino.cc/products/arduino-starter-kit-multi-language
 
-![](upload://t4HCMr3Sd489eJVbKzISby008UI.jpeg)
+![Front of box](upload://t4HCMr3Sd489eJVbKzISby008UI.jpeg)
 
-![](upload://ryY24FVj9t7NGWfFRTvcYwOT32f.jpeg)
+![Back of box](upload://ryY24FVj9t7NGWfFRTvcYwOT32f.jpeg)
 
-![](upload://jsY5LC2FihrGykoYM5jGcepiPeY.jpeg)
+![Kit contents](upload://jsY5LC2FihrGykoYM5jGcepiPeY.jpeg)

content/categories/hardware/nano-family/nano-33-ble-sense/_topics/about-the-nano-33-ble-sense/1.md

@@ -10,4 +10,4 @@ It comes with a series of embedded sensors:
 
 https://store.arduino.cc/products/arduino-nano-33-ble
 
-![](upload://yB1tsZjDfGrJhp7jUkhzIgfgXAf.jpeg)
+![Nano 33 BLE Sense](upload://yB1tsZjDfGrJhp7jUkhzIgfgXAf.jpeg)