Added Subdomain takeover via Medium

Ref - https://hackerone.com/reports/1034023

takeovers/medium-takeover.yaml

@@ -0,0 +1,19 @@
+id: medium-takeover
+
+info:
+  name: Medium Takeover Detection
+  author: rtcms
+  severity: high
+  tags: takeover
+  reference: https://github.com/EdOverflow/can-i-take-over-xyz/issues/206
+
+requests:
+  - method: GET
+    path:
+      - "{{BaseURL}}"
+
+    matchers:
+      - type: word
+        words:
+          - Oops! We couldn’t find that page
+          - Sorry about that