Update remaining collections

collections/html/head-basics.yaml

@@ -1,4 +1,4 @@
-slug: c/html-head-basics
+slug: html/head-basics
 name: HTML Head Basics
 featured: true
 snippetIds:

collections/react/rendering.yaml

@@ -1,4 +1,4 @@
-slug: c/react-rendering
+slug: react/rendering
 name: React Rendering
 miniName: Rendering
 parent: react

collections/react/testing.yaml

@@ -1,4 +1,4 @@
-slug: c/react-testing
+slug: react/testing
 name: React Testing
 shortName: Testing
 parent: react

hub.yaml

@@ -20,7 +20,7 @@ featuredListings:
 - js/data-structures
 - js/promises
 - js/comparison
-- c/html-head-basics
+- html/head-basics
 - css/centering
 - js/css-manipulation
 - js/url
@@ -31,13 +31,13 @@ featuredListings:
 - js/arrow-functions
 - js/performance
 - tips
-- c/react-rendering
+- react/rendering
 - js/colors
 - js/browser-capabilities
 - js/array-methods
 - js/array-tricks
 - js/object-key-transformations
-- c/react-testing
+- react/testing
 - css/hover-effects
 - js/string-casing
 - js/generators