chore: update readme

README.md

@@ -1,3 +1,37 @@
 # Drow HTTP
 
 Prometheus http query client of Python.
+
+Implemented prometheus http api:
+https://prometheus.io/docs/prometheus/latest/querying/api/
+
+## install
+
+    pip install drow-http
+
+## usage
+
+get client:
+
+    from drow_http import get_client
+
+    client = get_client("http://127.0.0.1:9090")
+
+query as vector:
+
+    result = client.query_as_vector("http_requests_total")
+    for s in result.series:
+        print(s.metric, s.value.timestamp, s.value.value)
+
+query range:
+
+    import time
+
+    end = time.time()
+    start = end - 60 * 60
+
+    result = client.query_range("http_requests_total", start=start, end=end)
+    for s in result.series:
+        print(s.metric)
+        for p in s.values:
+            print(p.timestamp, p.value)