update examples and add documentation

04-typestate/src/main.rs

@@ -11,7 +11,7 @@ struct CredentialManager<State = Locked> {
 }
 
 impl CredentialManager {
-    pub fn new() -> CredentialManager<Locked> {
+    pub fn new() -> CredentialManager {
         CredentialManager {
             entries: HashMap::new(),
             state: std::marker::PhantomData,
@@ -46,9 +46,9 @@ impl CredentialManager<Unlocked> {
 }
 
 fn main() {
-    let pw = CredentialManager::new();
-    let mut pw = pw.unlock("pssst");
-    pw.set("foo", "bar");
-    let val = pw.get("foo");
-    pw.lock();
+    let pw_locked = CredentialManager::new();
+    let mut pw_unlocked = pw_locked.unlock("pssst");
+    pw_unlocked.set("foo", "bar");
+    let val = pw_unlocked.get("foo");
+    let pw_locked = pw_unlocked.lock();
 }