docs: change contributor group name (Collaborator --> Collaborators) (#29553)

The name of the group also serves as the group tab's title in the docs
app and having "Collaborator" (singular) as a title for a list of people
didn't read well.
Changing th group name (and thus tab title) to "Collaborators" (plural).

PR Close #29553

aio/content/marketing/contributors.json

@@ -658,12 +658,12 @@
     "twitter": "samjulien",
     "website": "http://www.samjulien.com/",
     "bio": "Sam Julien builds software, articles, video courses, and campfires. A developer, speaker, writer, and GDE in the Pacific Northwest, Sam's favorite thing in the world is changing someone's life by teaching them to code.",
-    "group": "Collaborator",
+    "group": "Collaborators",
     "mentor": "gkalpak"
   },
   "JiaLiPassion": {
     "name": "JiaLi Passion",
-    "group": "Collaborator",
+    "group": "Collaborators",
     "mentor": "mhevery",
     "picture": "JiaLiPassion.jpg",
     "bio": "A programmer with passion, angular/zone.js guy! Web frontend engineer @sylabs"
@@ -671,19 +671,19 @@
   "cexbrayat": {
     "name": "Cédric Exbrayat",
     "mentor": "petebacondarwin",
-    "group": "Collaborator",
+    "group": "Collaborators",
     "picture": "cexbrayat.jpg",
     "bio": "Author of `Become a ninja with Angular (2+)` https://books.ninja-squad.com/angular - Angular trainer and @Ninja-Squad co-founder"
   },
   "CaerusKaru": {
     "name": "Adam Plumer",
-    "group": "Collaborator",
+    "group": "Collaborators",
     "mentor": "vikerman",
     "picture": "CaerusKaru.jpg"
   },
   "jbedard": {
     "name": "Jason Bedard",
-    "group": "Collaborator",
+    "group": "Collaborators",
     "mentor": "kyliau",
     "picture": "jbedard.png"
   },

aio/scripts/contributors/org_chart.jq

@@ -1,7 +1,7 @@
 # Produces a GraphViz Dot file from the data in the contributors.json file.
 # Documentation for this syntax at https://stedolan.github.io/jq/manual
 to_entries
-| map(select(.value.group=="Angular" or .value.group=="Collaborator"))
+| map(select(.value.group=="Angular" or .value.group=="Collaborators"))
 | map(.value |= {name: .name, lead: (.lead // .mentor // "")})
 | map(
    "\(.key|tojson) [ label = \(.value.name|tojson) ] ",