doc: add/update sample files

doc/sample/Exception.im

@@ -1,7 +1,7 @@
 try
     x = 0
     --v = Int parse:'342'
-catch (#err:number_format, err) in
+catch ($err:number_format, err) in
     x = 1
     --cout put:'Cannot parse integer string ({err})'
 catch (_, err) in

doc/sample/Incorrect.im

@@ -0,0 +1,5 @@
+var x = "Hello, world!"
+
+for i in 0 to:100 step:2 do
+  cout put:'Count is {i}'
+end

doc/sample/Simple.iasm

@@ -0,0 +1,9 @@
+@block [index:#1007]
+	br $L0004
+L0004:
+	ret.n
+@end
+
+@block [index:#1008]
+	ret
+@end

doc/sample/Simple.im

@@ -1,5 +1,3 @@
-var x = "Hello, world!".
+var x = 2 + 255 * 3 / 63.
 
-for (ch, cy) in x do
-    cout put:ch
-end
+cout put:x.