docs: initialize app for vertical tagging in course-discovery and add…

… an ADR for it (#4542)

* chore: initialize tagging app

* docs: add vertical tagging ADR

course_discovery/apps/tagging/apps.py

@@ -0,0 +1,6 @@
+from django.apps import AppConfig
+
+
+class TaggingConfig(AppConfig):
+    default_auto_field = 'django.db.models.BigAutoField'
+    name = 'course_discovery.apps.tagging'

course_discovery/settings/base.py

@@ -87,6 +87,7 @@
     'course_discovery.apps.publisher_comments',
     'course_discovery.apps.learner_pathway',
     'course_discovery.apps.taxonomy_support',
+    'course_discovery.apps.tagging',
 ]
 
 ES_APPS = [

docs/decisions/0031-vertical-content-tagging.rst

@@ -0,0 +1,52 @@
+31. Vertical Content Tagging
+=============================
+
+Status
+--------
+Accepted (January 2025)
+
+Context
+---------
+The Open edX `course-discovery` service currently lacks an efficient and flexible way to categorize courses by 
+granular subject areas and verticals. The existing mechanisms (e.g., tags, Primary Subject) are limited, primarily 
+partner-driven, and often misaligned with business-specific needs for taxonomy and categorization.
+
+For example, a partner might categorize a Python course under the broad umbrella of programming languages, aligning with general usage.
+However, the business may wish to categorize the same course under Data Science tools,
+highlighting its primary focus on enabling learners to apply Python in Data Science.
+
+It is important to note that here `partner` and `business` can represent distinct entities with different taxonomical needs. 
+However, in some installations, the partner and business could represent the same entity, so this distinction may not always apply.
+
+Objective
+-----------
+1. Introduce a structured approach to categorizing courses by  aligning them with specific business objectives
+2. Enable more effective classification of courses based on verticals, ensuring that courses can be easily discovered and grouped according to strategic priorities, thereby improving overall discoverability.
+
+Decision
+----------
+A new app will be created for the Vertical Content Tagging functionality.
+
+The following models will be added to the app:
+
+- **Vertical:** This model will store the list of verticals that can be associated with product types to define the portfolio of products 
+  that fall under a specific vertical.
+- **SubVertical:** This model stores sub-verticals, which can be associated with vertical filters. These sub-verticals allow further
+  categorization and refinement within a vertical.
+- **BaseVertical:** This abstract model will be used to associate vertical and sub-vertical filters across product types.
+- **CourseVertical:** This model will extend BaseVertical to enable the assignment of vertical and sub-vertical filters to courses.
+
+Currently, the intention is to support vertical tagging for courses only. In the future, 
+the same functionality can be extended to other product types (e.g., Programs, Degrees, etc.).
+
+A new user group will be created to grant access to the admin panel for assigning vertical and sub-vertical tags to courses.
+However, this user group will not have the permission to manage vertical and sub-vertical filters, this functionality will be restricted to superusers only.
+
+This new user group will be managed using a base settings configuration variable.
+
+Alternatives Considered
+-------------------------
+- Add New Models in course_metadata: Keeping functionality within a single app, simplifying integration. 
+  However, it risks app bloat, increased coupling, and reduced readability due to the large number of existing models.
+- Create a Separate Plugin: Decouples vertical tagging for better scalability and modularity, with a plug-and-play structure.
+  However, it requires significant initial effort, coordination, and limits Django ORM relationships with course-discovery models.