libs/libc/unistd/lib_getcwd.c: remove stray sched_unlock(). Also fixes several typos.

Documentation/NXGraphicsSubsystem.html

@@ -1332,7 +1332,7 @@ int nx_eventhandler(NXHANDLE handle);
   the CPU bandwidth calling nx_eventhandler repeatedly.
   <a href="#nxeventnotify"><code>nx_eventnotify()</code></a>
   may be called to get a signal event whenever a new incoming server
-  event is avaiable.
+  event is available.
 </p>
 <p>
   <b>Input Parameters:</b>

Documentation/NuttX.html

@@ -6528,7 +6528,7 @@ Mem:         29232       5920      23312      23312
         for download from the <a href="http://www.microchip.com">MicroChip</a> website, or
       </li>
       <li>
-        The Pinguino MIPS ELF toolchain avaiable from the Pinquino <a href="http://code.google.com/p/pinguino32/downloads/list">website</a>.
+        The Pinguino MIPS ELF toolchain available from the Pinguino <a href="http://code.google.com/p/pinguino32/downloads/list">website</a>.
       </li>
       <li>
         The MIPS SDE toolchain available from the <a href="http://www.mentor.com">Mentor Graphics</a> website.