Fix markdown documentation links (#35)

- Update/remove broken links
- Add appropriate ignore rules for example URLs and osquery site

.github/workflows/docs.yml

@@ -8,3 +8,6 @@ jobs:
     steps:
     - uses: actions/checkout@master
     - uses: gaurav-nelson/github-action-markdown-link-check@v1
+      with:
+        use-quiet-mode: 'yes'
+        config-file: .github/workflows/markdown-link-check-config.json

.github/workflows/markdown-link-check-config.json

@@ -0,0 +1,14 @@
+{
+    "ignorePatterns": [
+        {
+            "localhost": "localhost",
+            "osquery-downloads": "osquery.io/downloads",
+            "fleet.acme.org": "fleet.acme.org",
+            "fleet.corp.example.com": "fleet.corp.example.com"
+        }
+    ],
+    "retryOn429": true,
+    "retryCount": 2,
+    "fallbackRetryDelay": "2s",
+    "aliveStatusCodes": [200, 206]
+}