v1.1.0

fix multiple problems with the validation function and solving issue #1

• it is a host name validation function
• a trailing dot is valid
• without trailing dot, max len is 253
• with a trailing dot, max len is 254
• use table tests with error message checking
• clarify some error messages

Change tag from v1.1 to v1.1.0 for go doc and module.

v1.0.1

Code and API are unmodified.

• Modified the default branch name,
• Replace travis with github actions,
• Fix badges in README.

v1.0.0

Put RFC references in a list