Start versioning some jq tools

Serving suggestion:

> Can I use 'git branch --show-current' in that testsuite?

    Documentation/RelNotes/2.22.0.txt
    32: * "git branch" learned a new subcommand "--show-current".

> Well then which distros ship Git <2.22?

    $ wget -O- https://repology.org/api/v1/project/git |
      jq -r '
        import "version" as version ;

        map(select(.version | version::versionlt("2.22")))
        | sort_by(.repo, (.version | version::toversion))
        | map("\(.version)\t\(.repo)")
        | .[]
    ' | column -ts$'\t'

1 files changed, 5 insertions, 0 deletions

diff --git a/.jq/version.jq b/.jq/version.jq
new file mode 100644
index 0000000..d7d3d62
--- /dev/null
+++ b/.jq/version.jq
@@ -0,0 +1,5 @@
+def toversionnumber: try tonumber catch 0;
+
+def toversion: split(".") | map(toversionnumber);
+
+def versionlt(rhs): ( . | toversion) < ( rhs | toversion );