Describe more methods in mmts readme.

Author: kvap

README.md

@@ -28,14 +28,19 @@ Manages the database nodes.
 * `deploy(driver, ...)` - deploys a cluster using the specified `driver` and
 other parameters specific to that driver. Returns a `cluster` instance that is
 used in other methods.
-* `
+* `cluster->up(id)` - adds a node named `id` to the `cluster`.
+* `cluster->down(id)` - removes a node named `id` from the `cluster`.
+* `cluster->drop(src, dst, ratio)` - drop `ratio` packets flowing from node
+`src` to node `dst`.
+* `cluster->delay(src, dst, msec)` - delay packets flowing from node `src` to
+node `dst` by `msec` milliseconds.
 
 #### `troubleaux`
 
 This is the troublemaker that messes with the network, nodes and time.
 
-* `cause(cluster, trouble)` - causes the specified `trouble` in the specified
-`cluster`.
+* `cause(cluster, trouble, ...)` - causes the specified `trouble` in the
+specified `cluster` with some trouble-specific parameters.
 * `fix(cluster)` - fixes all troubles caused in the `cluster`.
 
 #### `valideaux`