draft: upgrading from nRF5 SDK to NCS article (#537)

### Summary

Draft for Ultrahuman's article on nRF5 SDK -> NCS journey.

Notable adjustments in this commit:
- Uncomment commented code
- Convert caps sub-headings to markdown sub-headings
- Convert bash script image to code snippet

### Test Plan

Visual check

_data/authors.yml

@@ -366,3 +366,9 @@ diondokter:
   blurb:
     is an experienced Rust and embedded software engineer at Tweede Golf. He also
     created and maintains a number of open source projects.
+gauravsingh:
+  name: Gaurav Singh
+  linkedin: https://www.linkedin.com/in/gaurav-singh-45596942
+  image: /img/author/gauravsingh.jpeg
+  blurb:
+    is a Senior Firmware Engineer at Ultrahuman. Gaurav previously worked on cloud chain monitoring systems and smart automobile technologies.