docs: add abagshaw as a contributor (#312)

* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>

.all-contributorsrc

@@ -88,6 +88,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "abagshaw",
+      "name": "Andrew Bagshaw",
+      "avatar_url": "https://avatars2.githubusercontent.com/u/8594541?v=4",
+      "profile": "https://github.com/abagshaw",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 7,