Fix link to "Entropy (information theory)" Wikipedia entry

Make "Entropy and information theory" inline link compatible with older markdown implementations.

fixes uccser#2565

Newer Markdown implementations (e.g. GitHub's as of this writing) properly render an inline link[0] whose link destination[1] includes parenthesis. Older ones fail, and, as a result, what should be rendered as:

href="https://en.wikipedia.org/wiki/Entropy_(information_theory)"

is instead rendered as:

href="https://en.wikipedia.org/wiki/Entropy_(information_theory"

(closing parenthesis elided/wrong URL)

Wrapping the link destination within angle brackets solves that issue in a way that should be forward-compatible.

[0] https://spec.commonmark.org/0.31.2/#inline-link
[1] https://spec.commonmark.org/0.31.2/#link-destination

csfieldguide/chapters/content/en/coding-introduction/sections/further-reading.md

@@ -5,7 +5,7 @@ James Gleick's book [The Information: A History, a Theory, a Flood](http://www.a
 ## Useful links
 
 - A good collection of resources related to all three kinds of coding is available in the [Bletchley Park Codes Resources](http://www.cimt.org.uk/resources/codes/)
-- [Entropy and information theory](https://en.wikipedia.org/wiki/Entropy_(information_theory))
+- [Entropy and information theory](<https://en.wikipedia.org/wiki/Entropy_(information_theory)>)
 - [History of information theory and its relationship to entropy in thermodynamics](https://en.wikipedia.org/wiki/History_of_entropy#Information_theory)
 - [Timeline of information theory](https://en.wikipedia.org/wiki/Timeline_of_information_theory)
 - [Shannon's seminal work in information theory](https://en.wikipedia.org/wiki/A_Mathematical_Theory_of_Communication)