Generating output fails if asciidoc_fields doesn't already exist.

[maihde]

Steps to reproduce:

1. Set --out to a folder that is empty and run generator.py

Observed behavior:
Generation fails with a folder not exists error.

Fix:

diff --git a/scripts/generators/asciidoc_fields.py b/scripts/generators/asciidoc_fields.py
index 8d4200bf..7b59aff2 100644
--- a/scripts/generators/asciidoc_fields.py
+++ b/scripts/generators/asciidoc_fields.py
@@ -27,6 +27,8 @@ def generate(nested, docs_only_nested, ecs_generated_version, out_dir):
     # fields docs now have a dedicated docs subdir: docs/fields
     fields_docs_dir = out_dir + '/fields'
 
+    ecs_helpers.make_dirs(fields_docs_dir)
+
     save_asciidoc(path.join(out_dir, 'index.asciidoc'), page_index(ecs_generated_version))
     save_asciidoc(path.join(fields_docs_dir, 'fields.asciidoc'), page_field_index(nested, ecs_generated_version))
     save_asciidoc(path.join(fields_docs_dir, 'field-details.asciidoc'), page_field_details(nested, docs_only_nested))

[kgeller]

Hi @maihde ! Thanks for catching this and providing a solution. We always welcome PRs, or we can put it into our backlog to fix ourselves at a future time.