include directory README (dbt-labs#4685)

* start of a README for the include directory

* minor updates

* minor updates after comments from gerda and emily

* trailing space issue?

* black formatting

* minor word change

* typo update

* minor fixes and changelog creation

* remove changelog

core/dbt/include/README.md

@@ -1 +1,15 @@
-# Include README
+# Include Module
+
+The Include module is reponsible for housing default macro definitions, starter project scaffold, and the html file used to generate the docs page.
+
+# Directories
+
+## `global_project`
+Defines the default implementations of jinja2 macros for `dbt-core` which can be overwritten in each adapter repo to work more in line with those adapter plugins. To view adapter specific jinja2 changes please check the relevant adapter repo [`adapter.sql` ](https://github.com/dbt-labs/dbt-bigquery/blob/main/dbt/include/bigquery/macros/adapters.sql) file in the `include` directory or in the [`impl.py`](https://github.com/dbt-labs/dbt-bigquery/blob/main/dbt/adapters/bigquery/impl.py) file for some ex. BigQuery (truncate_relation).
+
+## `starter_project`
+Produces the default project after running the `dbt init` command for the CLI. `dbt-cloud` initializes the project by using [dbt-starter-project](https://github.com/dbt-labs/dbt-starter-project).
+
+
+# Files
+ - `index.html` a file generated from [dbt-docs](https://github.com/dbt-labs/dbt-docs) prior to new releases and replaced in the `dbt-core` directory. It is used to generate the docs page after using the `generate docs` command in dbt.