Tweak asterisk formatting for plain-text readability (#2111)

In several exercise descriptions we use asterisks for purposes
other than markdown text emphasis.

Mostly that is to represent the concept of multiplication, though
in one instance we are simply referring to a literal asterisk.

On the website these unescaped asterisks would mess up the formatting,
half-emphasized text or invalid HTML.

However escaping the asterisks makes it harder to understand the
instructions when working in a local development environment rather
than in the online editor.

In other exercises we've chosen to format arithmetic formulae as
code rather than escape the asterisks, which works for both
environments.

I've therefore chosen to extend this choice to the files that
had escaped asterisks.

Author: kytrinyx

exercises/all-your-base/description.md

@@ -17,15 +17,15 @@ combination of powers of **b**.
 
 The number 42, *in base 10*, means:
 
-(4 \* 10^1) + (2 \* 10^0)
+`(4 * 10^1) + (2 * 10^0)`
 
 The number 101010, *in base 2*, means:
 
-(1 \* 2^5) + (0 \* 2^4) + (1 \* 2^3) + (0 \* 2^2) + (1 \* 2^1) + (0 \* 2^0)
+`(1 * 2^5) + (0 * 2^4) + (1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (0 * 2^0)`
 
 The number 1120, *in base 3*, means:
 
-(1 \* 3^3) + (1 \* 3^2) + (2 \* 3^1) + (0 \* 3^0)
+`(1 * 3^3) + (1 * 3^2) + (2 * 3^1) + (0 * 3^0)`
 
 I think you got the idea!
 

exercises/largest-series-product/description.md

@@ -4,8 +4,8 @@ Given a string of digits, calculate the largest product for a contiguous
 substring of digits of length n.
 
 For example, for the input `'1027839564'`, the largest product for a
-series of 3 digits is 270 (9 \* 5 \* 6), and the largest product for a
-series of 5 digits is 7560 (7 \* 8 \* 3 \* 9 \* 5).
+series of 3 digits is 270 `(9 * 5 * 6)`, and the largest product for a
+series of 5 digits is 7560 `(7 * 8 * 3 * 9 * 5)`.
 
 Note that these series are only required to occupy *adjacent positions*
 in the input; the digits need not be *numerically consecutive*.

exercises/minesweeper/description.md

@@ -11,7 +11,7 @@ mines adjacent to a given empty square and replaces that square with the
 count.
 
 The board is a rectangle composed of blank space (' ') characters. A mine
-is represented by an asterisk ('\*') character.
+is represented by an asterisk (`*`) character.
 
 If a given space has no adjacent mines at all, leave that square blank.
 

exercises/prime-factors/description.md

@@ -24,7 +24,10 @@ factors of 60: 2, 2, 3, and 5.
 
 You can check this yourself:
 
-- 2 \* 2 \* 3 * 5
-- = 4 * 15
-- = 60
-- Success!
+```text
+2 * 2 * 3 * 5
+= 4 * 15
+= 60
+```
+
+Success!