kvs: add rst format to inline docs

Problem: on the web version of the docs, which are
auto-generated, multiple lines of python appear on
the same line, and are formatted weirdly.

We can add rst format to the inline docs.

src/bindings/python/flux/kvs.py

@@ -478,20 +478,24 @@ class KVSDir(WrapperPimpl, abc.MutableMapping):
 
     KVS values can be read or written through this class's item accessor.  e.g.
 
-    mydir = KVSDir(flux_handle)
-    print(mydir["mykey"])
+    .. code-block :: python
 
-    mydir["newkey"] = "foo"
-    mydir.commit()
+       mydir = KVSDir(flux_handle)
+       print(mydir["mykey"])
 
+       mydir["newkey"] = "foo"
+       mydir.commit()
+    
     Any KVS directories accessed through the item accessor will share
     the same internal KVS transaction, so that only a single call to
     commit() is necessary.  e.g.
+    
+    .. code-block :: python
 
-    mydir = KVSDir(flux_handle)
-    subdir = mydir["subdir"]
-    subdir["anotherkey"] = "bar"
-    mydir.commit()
+       mydir = KVSDir(flux_handle)
+       subdir = mydir["subdir"]
+       subdir["anotherkey"] = "bar"
+       mydir.commit()
 
     Args:
         flux_handle: A Flux handle obtained from flux.Flux()