Twitter search input binding (#549)

* added docks for twitter search binding

* updated search query

reference/specs/bindings/twitter.md

@@ -0,0 +1,28 @@
+# Kubernetes Events Binding Spec
+
+```yml
+apiVersion: dapr.io/v1alpha1
+kind: Component
+metadata:
+  name: <name>
+spec:
+  type: bindings.twitter
+  metadata:
+  - name: consumerKey
+    value: ''
+  - name: consumerSecret
+    value: ''
+  - name: accessToken
+    value: ''
+  - name: accessSecret
+    value: ''
+  - name: query
+    value: ''
+```
+
+
+- `consumerKey` (required) is the Twitter API consumer key
+- `consumerSecret` (required) is the Twitter API consumer secret
+- `accessToken` (required) is the Twitter API access token
+- `accessSecret` (required) is the Twitter API access secret
+- `query` (required) is the Twitter search query (e.g. `dapr`)