documentation and typo fixes. By Dan Fandrich (dan AT coneharvesters.com)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

include/libbb.h

@@ -1174,7 +1174,7 @@ unsigned long long bb_makedev(unsigned int major, unsigned int minor) FAST_FUNC;
 
 /* "Keycodes" that report an escape sequence.
  * We use something which fits into signed char,
- * yet doesn't represent any valid Unicode characher.
+ * yet doesn't represent any valid Unicode character.
  * Also, -1 is reserved for error indication and we don't use it. */
 enum {
 	KEYCODE_UP       =  -2,

include/usage.h

@@ -2001,8 +2001,8 @@
      "\n	a	File is accessed" \
      "\n	c	File is modified" \
      "\n	e	Metadata changed" \
-     "\n	w	Writtable file is closed" \
-     "\n	0	Unwrittable file is closed" \
+     "\n	w	Writable file is closed" \
+     "\n	0	Unwritable file is closed" \
      "\n	r	File is opened" \
      "\n	D	File is deleted" \
      "\n	M	File is moved" \
@@ -3860,7 +3860,7 @@
      "\n	-l	Log changes in file labels to syslog" \
      "\n	-n	Don't change any file labels" \
      "\n	-q	Suppress warnings" \
-     "\n	-r dir	Use an altenate root path" \
+     "\n	-r dir	Use an alternate root path" \
      "\n	-e dir	Exclude directory" \
      "\n	-F	Force reset of context to match file_context for customizable files" \
      "\n	-o file	Save list of files with incorrect context" \