runtime(sh): Update sh syntax and add shDerefOffset to shDerefVarArray for bash (#13480)
Add shDerefOffset to shDerefVarArray.
Example code:
```bash
declare -a a=({a..z})
echo "${a[@]:1:3}"
```
Signed-off-by: Christian Brabandt <cb@256bit.org>diff --git a/runtime/syntax/sh.vim b/runtime/syntax/sh.vim
index 0fb10f0..e2b1947 100644
--- a/runtime/syntax/sh.vim
+++ b/runtime/syntax/sh.vim
@@ -531,7 +531,7 @@
endif
" sh ksh bash : ${var[... ]...} array reference: {{{1
-syn region shDerefVarArray contained matchgroup=shDeref start="\[" end="]" contains=@shCommandSubList nextgroup=shDerefOp,shDerefOpError
+syn region shDerefVarArray contained matchgroup=shDeref start="\[" end="]" contains=@shCommandSubList nextgroup=shDerefOp,shDerefOpError,shDerefOffset
" Special ${parameter OPERATOR word} handling: {{{1
" sh ksh bash : ${parameter:-word} word is default value