- updated _sidebar
- fixed some typos in previously updated pages

HSM.md

-In **hierarchical state machines** states are organized in a hierarchy. This means that states can be other state machines.  
+In **hierarchical state machines** states are organized in a hierarchy.  
+This means that states can be themselves other state machines.  
 
 ## Implementation
 In *skyward-boardcore* implementation, the **HSM** class extends the [EventHandler](EventHandler) class, as for FSMs.  
+HSM is also a template class, such as FSM.  
   
-The main difference is that we can specify super-state and perform transiotions to them.  
+The main difference is that we can specify also super-states and perform transitions to them.  
   
 Moreover, state methods should return a value of type `State`:
 ```cpp
@@ -44,7 +46,7 @@ Available public methods are:
 - **bool testState(State (T::\*test_state)(const Event&))**: test is the state machines is in a specific state (that is passed as a parameter).
 
 #### Standard Events
-As for FSMs, `EV_ENTRY` and `EV_EXIT` are automatically posted when entering or exiting a state. Moreover, by handling `EV_INIT` in a suprt-state we can perform the transition to the initial sub-state.  
+As for FSMs, `EV_ENTRY` and `EV_EXIT` are automatically posted when entering or exiting a state. Moreover, by handling `EV_INIT` in a super-state we can perform the transition to its initial sub-state.  
   
 You can find the complete implementation of the HSM class in `src/shared/events/HSM.h`.
 
@@ -85,7 +87,8 @@ class MyHSM : public HSM<MyHSM>
 {
 public:
     MyHSM()
-        : HSM(&MyHSM::state_initialization),  // set HSM initial state to state_S1
+        // set HSM initial state to state_initialization
+        : HSM(&MyHSM::state_initialization),  
           last_event(0)
     {
         // make this object to subscribe to TOPIC_1