Add missing builtins to sh.nanorc

See http://manpages.ubuntu.com/manpages/disco/man7/bash-builtins.7.html#synopsis

sh.nanorc

@@ -8,7 +8,7 @@ color green "(\{|\}|\(|\)|\;|\]|\[|`|\\|\$|<|>|!|=|&|\|)"
 color green "-[Ldefgruwx]\>"
 color green "-(eq|ne|gt|lt|ge|le|s|n|z)\>"
 ## builtins:
-color brightblue "\<(alias|bg|bind|break|builtin|cd|command|compgen|complete|continue|declare|dirs|disown|echo|enable|eval|exec|exit|export|fc|fg|getopts|hash|help|history|jobs|kill|let|local|logout|popd|printf|pushd|pwd|read|readonly|return|set|shift|shopt|source|suspend|test|times|trap|type|typeset|ulimit|umask|unalias|unset|wait)\>"
+color brightblue "\<(alias|bg|bind|break|builtin|caller|cd|command|compgen|complete|compopt|continue|declare|dirs|disown|echo|enable|eval|exec|exit|export|false|fc|fg|getopts|hash|help|history|jobs|kill|let|local|logout|mapfile|popd|printf|pushd|pwd|read|readarray|readonly|return|set|shift|shopt|source|suspend|test|times|trap|true|type|typeset|ulimit|umask|unalias|unset|wait)\>"
 ## not buitins:
 ## cat|chmod|chown|cp|env|grep|install|ln|make|mkdir|mv|rm|sed|tar|touch
 icolor brightgreen "^\s+[0-9A-Z_]+\s+\(\)"