docs(examples): replace emoji in example definitions with real logo URLs

The rename made emoji invalid under the URL-only `logo` schema, so the
example server definitions would not validate. Use the matching GitHub
organisation avatars for each example's real-world service (GitHub,
Atlassian, Cloudflare, Notion) so copy-paste templates pass validation
out of the box.

Signed-off-by: Mohammod Al Amin Ashik <maa.ashik00@gmail.com>

Author: its-mash

examples/complete-example.json

@@ -4,7 +4,7 @@
   "name": "GitHub",
   "alias": "gh",
   "description": "Interact with GitHub repositories, issues, pull requests, and more through the GitHub API.",
-  "logo": "🐙",
+  "logo": "https://avatars.githubusercontent.com/u/9919?v=4",
   "schema_version": "2.1",
   "categories": [
     "developer-tools",

examples/read-only-example.json

@@ -4,7 +4,7 @@
   "name": "Cloudflare Docs",
   "alias": "cfdocs",
   "description": "Search and browse Cloudflare documentation",
-  "logo": "📚",
+  "logo": "https://avatars.githubusercontent.com/u/314135?v=4",
   "schema_version": "2.1",
   "categories": [
     "documentation",

examples/remote-hosted-example.json

@@ -4,7 +4,7 @@
   "name": "Atlassian (Jira & Confluence)",
   "alias": "atlassian",
   "description": "Interact with Jira issues and Confluence pages",
-  "logo": "🔷",
+  "logo": "https://avatars.githubusercontent.com/u/168166?v=4",
   "schema_version": "2.1",
   "categories": [
     "productivity",

examples/sponsored-example.json

@@ -4,7 +4,7 @@
   "name": "Notion",
   "alias": "notion",
   "description": "Read and write Notion pages, databases, and blocks",
-  "logo": "📝",
+  "logo": "https://avatars.githubusercontent.com/u/4792552?v=4",
   "schema_version": "2.1",
   "categories": [
     "productivity",