Resolve "Extend documentation for subtree update and incremental eval"

Related to #20 (closed)

pages/docs/using.md

@@ -46,7 +46,7 @@ eq A.getB().input() = getInput();
 ```
 
 In other words, `OutputOnA` depends on `Input` of the same node, and `OutputOnB` depends on `Input` of its parent node.
-Currently, those dependencies have can be explicitly written down, or incremental evaluation can be used.
+Currently, those dependencies can be explicitly written down, or incremental evaluation can be used.
 
 ### Dependency tracking: Manually specified
 
@@ -61,7 +61,7 @@ B.OutputOnB canDependOn A.Input as dependencyB ;
 ### Dependency tracking: Automatically derived
 
 To automatically track dependencies, the two additional parameters `--incremental` and `--trace=flush` have to be provided to both RagConnect and (in the later stage) JastAdd.
-This will generate different implementation of RagConnect relying on enabled incremental evaluation of JastAdd.
+This will generate a different implementation of RagConnect relying on enabled incremental evaluation of JastAdd.
 The value for `incremental` has only been tested for `incremental=param`.
 The value for `trace` can include other values besides `flush`.
 
@@ -204,7 +204,7 @@ A message for a list endpoint can also be interpreted as an element of this list
 receive tree ReceiverRoot.Alfa ;
 ```
 
-Upon connection, the index to set the deserialized element to set, has to be given (`1` in the example below).
+Upon connection, the index of the deserialized element to set, has to be passed (`1` in the example below).
 The list must have enough elements once a message is received.
 
 ```java