chore(curriculum): changed external links to news articles in 4 challenges (#43373)

* changed 4 links

* fix wording

* change link as suggested by @gikf

curriculum/challenges/english/01-responsive-web-design/basic-css/use-hex-code-for-specific-colors.md

@@ -11,9 +11,9 @@ dashedName: use-hex-code-for-specific-colors
 
 Did you know there are other ways to represent colors in CSS? One of these ways is called hexadecimal code, or hex code for short.
 
-We usually use <dfn>decimals</dfn>, or base 10 numbers, which use the symbols 0 to 9 for each digit. <dfn>Hexadecimals</dfn> (or <dfn>hex</dfn>) are base 16 numbers. This means it uses sixteen distinct symbols. Like decimals, the symbols 0-9 represent the values zero to nine. Then A,B,C,D,E,F represent the values ten to fifteen. Altogether, 0 to F can represent a digit in hexadecimal, giving us 16 total possible values. You can find more information about [hexadecimal numbers here](https://en.wikipedia.org/wiki/Hexadecimal).
+We usually use <dfn>decimals</dfn>, or base 10 numbers, which use the symbols 0 to 9 for each digit. <dfn>Hexadecimals</dfn> (or <dfn>hex</dfn>) are base 16 numbers. This means it uses sixteen distinct symbols. Like decimals, the symbols 0-9 represent the values zero to nine. Then A,B,C,D,E,F represent the values ten to fifteen. Altogether, 0 to F can represent a digit in hexadecimal, giving us 16 total possible values. You can find more information about [hexadecimal numbers here](https://www.freecodecamp.org/news/hexadecimal-number-system/).
 
-In CSS, we can use 6 hexadecimal digits to represent colors, two each for the red (R), green (G), and blue (B) components. For example, `#000000` is black and is also the lowest possible value. You can find more information about the [RGB color system here](https://en.wikipedia.org/wiki/RGB_color_model).
+In CSS, we can use 6 hexadecimal digits to represent colors, two each for the red (R), green (G), and blue (B) components. For example, `#000000` is black and is also the lowest possible value. You can find more information about the [RGB color system here](https://www.freecodecamp.org/news/rgb-color-html-and-css-guide/#whatisthergbcolormodel).
 
 ```css
 body {

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/euler-method.md

@@ -8,7 +8,7 @@ dashedName: euler-method
 
 # --description--
 
-Euler's method numerically approximates solutions of first-order ordinary differential equations (ODEs) with a given initial value. It is an explicit method for solving initial value problems (IVPs), as described in [the wikipedia page](<https://en.wikipedia.org/wiki/Euler method> "wp: Euler method").
+Euler's method numerically approximates solutions of first-order ordinary differential equations (ODEs) with a given initial value. It is an explicit method for solving initial value problems (IVPs), as described in [this article](<https://www.freecodecamp.org/news/eulers-method-explained-with-examples/> "news: Euler's Method Explained with Examples").
 
 The ODE has to be provided in the following form:
 

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/hash-join.md

@@ -8,7 +8,7 @@ dashedName: hash-join
 
 # --description--
 
-An [inner join](https://en.wikipedia.org/wiki/Join_(SQL)#Inner_join "wp: Join\_(SQL)#Inner_join") is an operation that combines two data tables into one table, based on matching column values. The simplest way of implementing this operation is the [nested loop join](<https://en.wikipedia.org/wiki/Nested loop join> "wp: Nested loop join") algorithm, but a more scalable alternative is the [hash join](<https://en.wikipedia.org/wiki/hash join> "wp: hash join") algorithm.
+An [inner join](https://www.freecodecamp.org/news/sql-join-types-inner-join-vs-outer-join-example/#how-to-use-an-inner-join-in-sql "news: SQL Join Types – Inner Join VS Outer Join Example#How to Use an INNER JOIN in SQL") is an operation that combines two data tables into one table, based on matching column values. The simplest way of implementing this operation is the [nested loop join](<https://en.wikipedia.org/wiki/Nested loop join> "wp: Nested loop join") algorithm, but a more scalable alternative is the [hash join](<https://en.wikipedia.org/wiki/hash join> "wp: hash join") algorithm.
 
 The "hash join" algorithm consists of two steps:
 

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/y-combinator.md

@@ -8,7 +8,7 @@ dashedName: y-combinator
 
 # --description--
 
-In strict [functional programming](<https://en.wikipedia.org/wiki/Functional programming> "wp: functional programming") and the [lambda calculus](<https://en.wikipedia.org/wiki/lambda calculus> "wp: lambda calculus"), functions (lambda expressions) don't have state and are only allowed to refer to arguments of enclosing functions. This rules out the usual definition of a recursive function wherein a function is associated with the state of a variable and this variable's state is used in the body of the function. The [Y combinator](https://mvanier.livejournal.com/2897.html) is itself a stateless function that, when applied to another stateless function, returns a recursive version of the function. The Y combinator is the simplest of the class of such functions, called [fixed-point combinators](<https://en.wikipedia.org/wiki/Fixed-point combinator> "wp: fixed-point combinator").
+In strict [functional programming](<https://www.freecodecamp.org/news/the-principles-of-functional-programming/> "news: the principles of functional programming") and the [lambda calculus](<https://en.wikipedia.org/wiki/lambda calculus> "wp: lambda calculus"), functions (lambda expressions) don't have state and are only allowed to refer to arguments of enclosing functions. This rules out the usual definition of a recursive function wherein a function is associated with the state of a variable and this variable's state is used in the body of the function. The [Y combinator](https://mvanier.livejournal.com/2897.html) is itself a stateless function that, when applied to another stateless function, returns a recursive version of the function. The Y combinator is the simplest of the class of such functions, called [fixed-point combinators](<https://en.wikipedia.org/wiki/Fixed-point combinator> "wp: fixed-point combinator").
 
 # --instructions--