Add tools and external links

_doc/accessibility/colors/color-contrast.md

@@ -67,6 +67,7 @@ If you don't see these tools, go to `about:config` and search the property "gfx.
 
 ### Tools
 
+* [Colour Contrast Analyser (software)](https://www.tpgi.com/color-contrast-checker/)
 * [Color review](https://color.review/)
 * [Button Contrast Checker](https://www.aditus.io/button-contrast-checker/)
 * [A11Y Color Contrast Accessibility Validator](https://color.a11y.com/Contrast/)

_doc/accessibility/mandatory-elements/valid-source-code.md

@@ -48,5 +48,10 @@ A source code is valid when:
 * the attributes respect the writing rules (for example, no obsolete elements are present);
 * the attribute values respect the writing rules (for example, duplicate ID values are not compliant).
 
+### Tools
+
+* [HTML Validator (bookmarklet)](https://dequeuniversity.com/validator)
+* [Serialized DOM checker (bookmarklet)](https://gist.github.com/stevefaulkner/c7087f72af0517dd60ffbd65acb850f8)
+
 *[DOM]: Document Object Model
 *[DTD]: Document Type Definition

_doc/sources.md

@@ -6,7 +6,7 @@ title: Sources
 A large part of the texts have been translated from official sources of the RGAA. You can find these documents here:
 
 * [Web Content Accessibility Guidelines 2.1](https://www.w3.org/TR/WCAG21/)
-* [The official version of the RGAA v4](https://www.numerique.gouv.fr/publications/rgaa-accessibilite/)
+* [The official RGAA last version (fr)](https://www.numerique.gouv.fr/publications/rgaa-accessibilite/)
 * [User impact (fr)](https://disic.github.io/guide-impacts_utilisateurs/index.html)
 * [Designer's guidelines (fr)](https://disic.github.io/guide-concepteur/4-navigation.html)
 * [Integrator's guidelines (fr)](https://disic.github.io/guide-integrateur/index.html)