tools: add remark-lint configuration in .remarkrc

Specifies the configuration for remark-lint, a markdown linter.

This configuration does not cause any warnings on any of the currently
present *.md files (ignoring thirdparty).

It is useful not only for possible future tooling that would check the
markdown files syntax, but also as a configuration for editor plugins,
e.g. linter-markdown for atom-linter.

Refs: #7637
Refs: #7727
Refs: #7757
PR-URL: #7729
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Robert Jefe Lindstaedt <robert.lindstaedt@gmail.com>

.remarkrc

@@ -0,0 +1,35 @@
+{
+  "plugins": {
+    "remark-lint": {
+      "code-block-style": false,
+      "definition-case": false,
+      "emphasis-marker": false,
+      "first-heading-level": false,
+      "heading-increment": false,
+      "list-item-content-indent": false,
+      "list-item-bullet-indent": false,
+      "list-item-indent": false,
+      "list-item-spacing": false,
+      "maximum-heading-length": false,
+      "maximum-line-length": false,
+      "no-consecutive-blank-lines": false,
+      "no-duplicate-headings": false,
+      "no-emphasis-as-heading": false,
+      "no-file-name-articles": false,
+      "no-file-name-irregular-characters": false,
+      "no-heading-punctuation": false,
+      "no-html": false,
+      "no-inline-padding": false,
+      "no-shell-dollars": false,
+      "no-shortcut-reference-link": false,
+      "no-literal-urls": false,
+      "no-missing-blank-lines": false,
+      "no-multiple-toplevel-headings": false,
+      "no-undefined-references": false,
+      "ordered-list-marker-style": false,
+      "ordered-list-marker-value": false,
+      "table-pipe-alignment": false,
+      "unordered-list-marker-style": false
+    }
+  }
+}