readme: add rst code blocks (#50)

README.rst

@@ -9,9 +9,9 @@ user to log the model metrics as the training progresses.
 
 The interface consists of three main methods:
 
-1. `dvclive.init(path)` - initializes dvclive logger. The metrics will be saved under `path`.
+1. :code:`dvclive.init(path)` - initializes dvclive logger. The metrics will be saved under :code:`path`.
 
-2. `dvclive.log(metric, value, step)` - logs the metric value. The value and step will be appended to `path/{metric}.tsv` file. The step value is optional.
+2. :code:`dvclive.log(metric, value, step)` - logs the metric value. The value and step will be appended to :code:`path/{metric}.tsv` file. The step value is optional.
 
-3. `dvclive.next_step()` - signals `dvclive` that current step has ended. Executed automatically if `metric` is logged again.
+3. :code:`dvclive.next_step()` - signals :code:`dvclive` that current step has ended. Executed automatically if :code:`metric` is logged again.