✅ Send "Accept-Encoding" HTTP header when checking "help.github.com"

Without the "Accept-Encoding" HTTP header GitHub blocks the requests
made to "help.github.com".

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

See also:

* github/docs#17358
* tcort/markdown-link-check#201

Author: alrra

tests/check_links_from_markdown_files.sh

@@ -6,7 +6,11 @@ cd "$(dirname "${BASH_SOURCE[0]}")" \
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 check_links() {
-    npx markdown-link-check@^3 --quiet --retry "$file"
+    npx markdown-link-check@^3 \
+        --config markdown-link-check.json \
+        --quiet \
+        --retry \
+        "$file"
 }
 
 check_markdown_files check_links

tests/markdown-link-check.json

@@ -0,0 +1,10 @@
+{
+    "httpHeaders": [
+        {
+            "urls": ["https://help.github.com"],
+            "headers": {
+                "Accept-Encoding": "br, gzip, deflate"
+            }
+        }
+    ]
+}