docs: update WCAG links and references

Author: mrholek

.github/CONTRIBUTING.md

@@ -165,7 +165,7 @@ Please use following commit message format.
 
 [Adhere to the Code Guide.](http://codeguide.co/#css)
 
-- When feasible, default color palettes should comply with [WCAG color contrast guidelines](http://www.w3.org/TR/WCAG20/#visual-audio-contrast).
+- When feasible, default color palettes should comply with [WCAG color contrast guidelines](https://www.w3.org/TR/WCAG/#distinguishable).
 - Except in rare cases, don't remove default `:focus` styles (via e.g. `outline: none;`) without providing alternative styles. See [this A11Y Project post](http://a11yproject.com/posts/never-remove-css-outlines) for more details.
 
 ### JS

docs/content/getting-started/accessibility.md

@@ -10,7 +10,7 @@ CoreUI for Bootstrap provides an easy-to-use framework of ready-made styles, lay
 
 ## Overview and limitations
 
-The overall accessibility of any project built with CoreUI for Bootstrap depends in large part on the author's markup, additional styling, and scripting they've included. However, provided that these have been implemented correctly, it should be perfectly possible to create websites and applications with CoreUI for Bootstrap that fulfill [<abbr title="Web Content Accessibility Guidelines">WCAG</abbr> 2.1](https://www.w3.org/TR/WCAG21/) (A/AA/AAA), [Section 508](https://www.section508.gov/), and similar accessibility standards and requirements.
+The overall accessibility of any project built with Bootstrap depends in large part on the author's markup, additional styling, and scripting they've included. However, provided that these have been implemented correctly, it should be perfectly possible to create websites and applications with Bootstrap that fulfill [<abbr title="Web Content Accessibility Guidelines">WCAG</abbr> 2.2](https://www.w3.org/TR/WCAG/) (A/AA/AAA), [Section 508](https://www.section508.gov/), and similar accessibility standards and requirements.
 
 ### Structural markup
 
@@ -24,7 +24,7 @@ Because CoreUI for Bootstrap components are purposely designed to be fairly gene
 
 ### Color contrast
 
-Some combinations of colors that currently make up CoreUI for Bootstrap default palette—used throughout the framework for things such as button variations, alert variations, form validation indicators—may lead to *insufficient* color contrast (below the recommended [WCAG 2.1 text color contrast ratio of 4.5:1](https://www.w3.org/TR/WCAG21/#contrast-minimum) and the [WCAG 2.1 non-text color contrast ratio of 3:1](https://www.w3.org/TR/WCAG21/#non-text-contrast)), particularly when used against a light background. Authors are encouraged to test their specific uses of color and, where necessary, manually modify/extend these default colors to ensure adequate color contrast ratios.
+Some combinations of colors that currently make up Bootstrap's default palette—used throughout the framework for things such as button variations, alert variations, form validation indicators—may lead to *insufficient* color contrast (below the recommended [WCAG 2.2 text color contrast ratio of 4.5:1](https://www.w3.org/TR/WCAG/#contrast-minimum) and the [WCAG 2.2 non-text color contrast ratio of 3:1](https://www.w3.org/TR/WCAG/#non-text-contrast)), particularly when used against a light background. Authors are encouraged to test their specific uses of color and, where necessary, manually modify/extend these default colors to ensure adequate color contrast ratios.
 
 ### Visually hidden content
 
@@ -51,7 +51,7 @@ On browsers that support `prefers-reduced-motion`, and where the user has *not*
 
 ## Additional resources
 
-- [Web Content Accessibility Guidelines (WCAG) 2.1](https://www.w3.org/TR/WCAG21/)
+- [Web Content Accessibility Guidelines (WCAG) 2.2](https://www.w3.org/TR/WCAG/)
 - [The A11Y Project](https://www.a11yproject.com/)
 - [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
 - [Tenon.io Accessibility Checker](https://tenon.io/)

scss/_functions.scss

@@ -177,7 +177,7 @@ $_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003
   @return if($l1 > $l2, divide($l1 + .05, $l2 + .05), divide($l2 + .05, $l1 + .05));
 }
 
-// Return WCAG2.1 relative luminance
+// Return WCAG2.2 relative luminance
 // See https://www.w3.org/TR/WCAG/#dfn-relative-luminance
 // See https://www.w3.org/TR/WCAG/#dfn-contrast-ratio
 @function luminance($color) {

scss/_variables.scss

@@ -79,7 +79,7 @@ $colors: (
 // scss-docs-end colors-map
 
 // The contrast ratio to reach against white, to determine if color changes from "light" to "dark". Acceptable values for WCAG 2.0 are 3, 4.5 and 7.
-// See https://www.w3.org/TR/WCAG20/#visual-audio-contrast-contrast
+// See https://www.w3.org/TR/WCAG/#contrast-minimum
 $min-contrast-ratio:   4.5 !default;
 
 // Customize the light and dark text colors for use in our color contrast function.

scss/mixins/_visually-hidden.scss

@@ -24,7 +24,7 @@
 // Use to only display content when it's focused, or one of its child elements is focused
 // (i.e. when focus is within the element/container that the class was applied to)
 //
-// Useful for "Skip to main content" links; see https://www.w3.org/TR/2013/NOTE-WCAG20-TECHS-20130905/G1
+// Useful for "Skip to main content" links; see https://www.w3.org/WAI/WCAG22/Techniques/general/G1.html
 
 @mixin visually-hidden-focusable() {
   &:not(:focus):not(:focus-within) {