Ignore all includes directories when linting (gravitational#201)

The intention in gravitational#192 was to ignore directories containing partials when
linting, since (a) these partials would be included within docs pages
when linting anyway, and (b) the linter returns errors when encountering
default parameter assignments within partials.

The change in gravitational#192 ignored includes in
'content/*/docs/pages/includes/*'.

However, in the `gravitational/teleport` CI container, docs content is
mounted to `content/`, without a version directory. This means that
default parameter assignments in `gravitational/teleport` partials still
fail the linter, since the partial URL would be something like
`content/docs/pages/includes/add-role-to-user.mdx`.

This change makes the pattern for ignoring partials more general so it
matches any file path with an `/includes/` segment.

package.json

@@ -21,7 +21,7 @@
     "lint": "yarn base:eslint --fix && yarn base:prettier --write -l",
     "lint-check": "yarn base:eslint && yarn base:prettier --check",
     "typecheck": "tsc --noEmit --skipLibCheck --incremental --tsBuildInfoFile node_modules/.cache/tsc/tsbuildinfo --project .",
-    "markdown-lint": "remark 'content/**/docs/pages/**/*.mdx' --frail --ignore-pattern 'content/*/docs/pages/includes/*' --silently-ignore",
+    "markdown-lint": "remark 'content/**/docs/pages/**/*.mdx' --frail --ignore-pattern '**/includes/**' --silently-ignore",
     "markdown-lint-external-links": "WITH_EXTERNAL_LINKS=true yarn markdown-lint",
     "markdown-fix": "FIX=true yarn markdown-lint -o"
   },