code review from Josh and Robert

@@ -22,20 +22,20 @@
      anything at all.  For example, we could use an arena containing the
      integers minpid through maxpid to allocate process IDs.  For uses of this
      nature, prefer id_space(9F) instead.
 
      vmem_create() and vmem_destroy() create and destroy vmem arenas.  In
-     order to differentiate between arenas used for adresses and arenas used
+     order to differentiate between arenas used for addresses and arenas used
      for identifiers, the VMC_IDENTIFIER flag is passed to vmem_create().
      This prevents identifier exhaustion from being diagnosed as general
      memory failure.
 
    Spans
      We represent the integers in an arena as a collection of spans, or
      contiguous ranges of integers.  For example, the kernel heap consists of
      just one span: [kernelheap, ekernelheap).  Spans can be added to an arena
-     in two ways: explicitly, by vmem_add(), or implicitly, by importing, as
+     in two ways: explicitly, by vmem_add(); or implicitly, by importing, as
      described in Imported Memory below.
 
    Segments
      Spans are subdivided into segments, each of which is either allocated or
      free.  A segment, like a span, is a contiguous range of integers.  Each