chore: migrate contrib markdown lint to rumdl

Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>

Author: zeitlinger

.github/config/.markdownlint-cli2.yaml

@@ -0,0 +1,11 @@
+[global]
+disable = ["MD059", "line-length", "no-inline-html", "MD041", "ul-style", "fenced-code-language"]
+
+[no-duplicate-heading]
+siblings-only = true
+
+[no-trailing-punctuation]
+punctuation = ".,;:"
+
+[ol-prefix]
+style = "ordered"

.github/config/.rumdl.toml

@@ -1,16 +1,16 @@
 [tools]
 "github:grafana/flint" = "0.21.0"
 lychee = "0.23.0"
-markdownlint-cli2 = "0.22.0"
+rumdl = "0.1.83"
 
 [env]
 FLINT_CONFIG_DIR = ".github/config"
 
 [tasks.lint]
-description = "Run link checks"
+description = "Run markdown and link linting"
 raw_args = true
-run = "flint run lychee"
+run = "flint run lychee rumdl"
 
 [tasks."lint:fix"]
 description = "Auto-fix lint issues"
-run = "flint run --fix"
+run = "flint run --fix rumdl"