Improve README.md for newcomers

README.md

@@ -1,5 +1,24 @@
 This [dbt](https://github.com/fishtown-analytics/dbt) package contains macros that can be (re)used across dbt projects.
 
+## Getting started
+
+To use dbt-utils:
+
+1. Reference the package in your dbt project by creating a `packages.yml` file, which should look something like:
+
+  ```
+  packages:
+    - git: "https://github.com/fishtown-analytics/dbt-utils.git"
+      revision: 0.1.22
+  ```
+The revision key pins the dependency on a specific release of dbt-utils. Consult the [releases](https://github.com/fishtown-analytics/dbt-utils/releases) for information about the latest release.
+
+2. Install the package by executing `dbt deps`
+
+Detailed information on packages can be found in dbt's documentation in the [Package Management](https://docs.getdbt.com/docs/package-management) section.
+
+----
+
 ## Macros
 ### Cross-database
 #### current_timestamp ([source](macros/cross_db_utils/current_timestamp.sql))
@@ -132,7 +151,7 @@ version: 2
 
 models:
   - name: model_name
-    tests:   
+    tests:
       - dbt_utils.recency:
           datepart: day
           field: created_at
@@ -152,7 +171,7 @@ models:
       - name: col_name
         tests:
           - dbt_utils.at_least_one
-      
+
 
 ```