Add pip and conda badges to installation docs

website/docs/usage/index.jade

@@ -23,6 +23,7 @@ p
         >>> nlp = spacy.load('en')
 
 +h(2, "pip") pip
+    +badge("pipy")
 
 p Using pip, spaCy releases are currently only available as source packages.
 
@@ -39,6 +40,7 @@ p
     pip install spacy
 
 +h(2, "conda") conda
+    +badge("conda")
 
 p
     |  Thanks to our great community, we've finally re-added conda support. You