Build pipelines for the Jenkins build system are configured in Groovy,
however since their filename is always `Jenkinsfile`, micro doesn't
recognize them as Groovy, and doesn't add syntax highlighting.
This small commit simply adds `Jenkinsfile` and `jenkinsfile` as file
names recognized as Groovy.
Odin is a general-purpose programming language with distinct typing,
built for high performance, modern systems, and built-in data-oriented
data types. The Odin Programming Language, the C alternative for
the joy of programming. The Data-Oriented Language for Sane Software
Development.
https://odin-lang.org/https://odin-lang.org/docs/overview/https://github.com/odin-lang/Odin
