Fix some errors in the documentation and other minor issues (#42)

Somewhat notable changes in this commit:
- The 'set +r' bugfix (re: 74b41621) is now documented in the
  changelog.
- Missing options have been added to the synopsis section of the
  ksh man page.
- The minor formatting fix from https://github.com/ksh-community/ksh/pull/5
  has been applied to the ksh man page.
- A few fixes from 5e747cfb
  have been applied to the ksh man page.
- The man page fixes from https://github.com/att/ast/pull/353
  have been applied, being:
  - An addition to document the behavior of 'set -H'.
  - A fix for the cd section appending rksh93.
  - A fix for some options being indented too far.
  - Removal of a duplicate section documenting '-D'.
  - Reordering the options for 'set' in alphabetical order.
  - A minor fix for the documentation of 'ksh -i'.

src/cmd/ksh93/tests/functions.sh

@@ -1262,7 +1262,7 @@ $SHELL -c 'PATH=/dev/null; function fn { unset -f fn; true; }; fn; fn' 2> /dev/n
 # Check if environment variables passed while invoking a function are exported
 # https://github.com/att/ast/issues/32
 unset foo
-function f2 { env | grep -q "^foo" || err_exit "Environment variable is not propogated from caller function"; }
+function f2 { env | grep -q "^foo" || err_exit "Environment variable is not propagated from caller function"; }
 function f1 { f2; env | grep -q "^foo" || err_exit "Environment variable is not passed to a function"; }
 foo=bar f1