Added new file on bugs, purged some errors in classes-doc

doc/classes

@@ -20,5 +20,5 @@ reset_bug(): resets the problems with a bug in crafty that causes a key-down-eve
              when the JSDSH-Tab is the one the browser falls back to after closing another tab.
              (Strange, I know…).
              If this happens, DON'T CLICK ANOTHER OBJECT! Open the JS-console and run reset_bug() manually.
-             If you accidantily clicke ONE other object, it is still possible to get back to the old state
+             If you accidentily clicke ONE other object, it is still possible to get back to the old state
              Manually reset_bug(), de- and refocus the window, and run reset_bug() once more.

doc/known_bugs

@@ -0,0 +1,22 @@
+Currently, there are two known bugs in JSDSH:
+
+=== "Gravity" ===
+
+==== Reproduce ====
+
+This bug is present at least in firefox and chrome(ium)
+
+Open JSDSH, then open a new tab. Close this tab, usually you will fall back into JSDSH. Click on any player
+or creature. This will cause this creature to "fall down" (that's where the name comes from), this means that
+it thinks there's a permanent key event from arrow-down.
+
+==== Reason ====
+
+The reason hasn't been tracked down, but is likely to be an error in Crafty.js itself.
+
+==== Countermeasures ====
+
+If this happens, DON'T CLICK ANOTHER OBJECT! Open the JS-console and trigger the function reset_bug() manually.
+If you accidentily clicked ONE other object, it is still possible to get back to the old state:
+Manually reset_bug(), de- and refocus the window, and trigger reset_bug() once more.
+