Add High-Level overview to Namespaces doc. (#6234)

* Add High-Level overview to Namespaces doc.

* Advanced levels.

* Update docs/understanding-airbyte/namespaces.md

Co-authored-by: Sherif A. Nada <snadalive@gmail.com>

Co-authored-by: Abhi Vaidyanatha <abhivaidyanatha@Abhis-MacBook-Pro.local>
Co-authored-by: Sherif A. Nada <snadalive@gmail.com>

docs/understanding-airbyte/namespaces.md

@@ -1,5 +1,22 @@
 # Namespaces
 
+## High-Level Overview
+
+{% hint style="info" %}
+The high-level overview contains all the information you need to use Namespaces when pulling from APIs. Information past that can be read for advanced or educational purposes.
+{% endhint %}
+
+When looking through our connector docs, you'll notice that some sources and destinations support "Namespaces." These allow you to organize and separate your data into groups in the destination if the destination supports it. For example, in a database, a namespace could be a schema in the database. If your desired destination doesn't support it, you can ignore this feature.
+
+Note that this is the location that both your normalized and raw data will get written to. Your raw data will show up with the prefix `_airbyte_raw_` in the namespace you define. If you don't enable basic normalization, you will only receive the raw tables. 
+
+If only your destination supports namespaces, you have two simple options. **This is the most likely case**, as all HTTP APIs currently don't support Namespaces.
+
+1. Replicate to the default namespace in the destination, which will differ based on your destination.
+2. Create a "Custom Format" to rename the namespace that your data will be replicated into.
+
+If both your desired source and destination support namespaces, your use case is probably replication-focused and more advanced, so continue reading.
+
 ## What is a Namespace?
 
 Technical systems often group their underlying data into namespaces with each namespace's data isolated from another namespace. This isolation allows for better organisation and flexibility, leading to better usability.