Fix various minor problems and update the documentation (#237)

These are minor fixes I've accumulated over time. The following
changes are somewhat notable:

- Added a missing entry for 'typeset -s' to the man page.
- Add strftime(3) to the 'see also' section. This and the date(1)
  addition are meant to add onto the documentation for 'printf %T'.
- Removed the man page the entry for ksh reading $PWD/.profile on
  login. That feature was removed in commit aa7713c2.
- Added date(1) to the 'see also' section of the man page.
- Note that the 'hash' command can be used instead of 'alias -t' to
  workaround one of the caveats listed in the man page.
- Use an 'out of memory' error message rather than 'out of space'
  when memory allocation fails.
- Replaced backticks with quotes in some places for consistency.
- Added missing documentation for the %P date format.
- Added missing documentation for the printf %Q and %p formats
  (backported from ksh2020: https://github.com/att/ast/pull/1032).
- The comments that show each builtin's options have been updated.

src/lib/libast/disc/memfatal.c

@@ -59,7 +59,7 @@ nomalloc(Vmalloc_t* region, int type, void* obj, Vmdisc_t* disc)
 #endif
 	case VM_NOMEM:
 		vmstat(region, &st);
-		error(ERROR_SYSTEM|3, "storage allocator out of space on %lu byte request ( region %lu segments %lu busy %lu:%lu:%lu free %lu:%lu:%lu )", (size_t)obj, st.extent, st.n_seg, st.n_busy, st.s_busy, st.m_busy, st.n_free, st.s_free, st.m_free);
+		error(ERROR_SYSTEM|3, "storage allocator out of memory on %lu byte request ( region %lu segments %lu busy %lu:%lu:%lu free %lu:%lu:%lu )", (size_t)obj, st.extent, st.n_seg, st.n_busy, st.s_busy, st.m_busy, st.n_free, st.s_free, st.m_free);
 		return(-1);
 	}
 	return(0);

src/lib/libast/disc/sfdcdio.c

@@ -88,7 +88,7 @@ int		type;
 	}
 
 	if(done < n && (di->cntl & FDIRECT) )
-	{	/* turn off directIO for remaining IO operation */
+	{	/* turn off direct IO for remaining IO operation */
 		di->cntl &= ~FDIRECT;
 		(void)fcntl(f->file, F_SETFL, di->cntl);
 	}