_content/blog: fix broken link to design document in why-generics

The Markdown link to the design document contains an invalid
line break between the description and the URL, causing the
link to be rendered incorrectly.

Also mention that generics are referred to as "type parameters"
in the spec.

Fixes golang/go#57421

Change-Id: I2acef0af0fa54700768f00d0103f6ea161c87c39
Reviewed-on: https://go-review.googlesource.com/c/website/+/458795
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>

_content/blog/why-generics.md

@@ -358,9 +358,9 @@ discuss a design for how we think we can add them to the language.
 
 Note added January 2022: This blog post was written in 2019 and does
 not describe the version of generics that was finally adopted.
-For updated information please see [the language
-spec](https://go.dev/ref/spec) and [the generics design document]
-(https://go.dev/design/43651-type-parameters).
+For updated information please see the description of type parameters in
+[the language spec](https://go.dev/ref/spec) and
+[the generics design document](https://go.dev/design/43651-type-parameters).
 
 At this year's Gophercon Robert Griesemer and I published
 [a design draft](https://github.com/golang/proposal/blob/master/design/go2draft-contracts.md)