exercises(rna-transcription): sync docs (#516)

Reflect the upstream change [1].

[1] exercism/problem-specifications@beed3cce0168

exercises/practice/rna-transcription/.docs/instructions.md

@@ -1,6 +1,6 @@
 # Instructions
 
-Given a DNA strand, return its RNA complement (per RNA transcription).
+Your task is determine the RNA complement of a given DNA sequence.
 
 Both DNA and RNA strands are a sequence of nucleotides.
 
@@ -14,3 +14,7 @@ Given a DNA strand, its transcribed RNA strand is formed by replacing each nucle
 - `C` -> `G`
 - `T` -> `A`
 - `A` -> `U`
+
+~~~~exercism/note
+If you want to look at how the inputs and outputs are structured, take a look at the examples in the test suite.
+~~~~

exercises/practice/rna-transcription/.docs/introduction.md

@@ -0,0 +1,16 @@
+# Introduction
+
+You work for a bioengineering company that specializes in developing therapeutic solutions.
+
+Your team has just been given a new project to develop a targeted therapy for a rare type of cancer.
+
+~~~~exercism/note
+It's all very complicated, but the basic idea is that sometimes people's bodies produce too much of a given protein.
+That can cause all sorts of havoc.
+
+But if you can create a very specific molecule (called a micro-RNA), it can prevent the protein from being produced.
+
+This technique is called [RNA Interference][rnai].
+
+[rnai]: https://admin.acceleratingscience.com/ask-a-scientist/what-is-rnai/
+~~~~