Add conceptual overview page to docs

docs/docs/concepts.md

@@ -0,0 +1,20 @@
+# Conceptual overview
+
+<!--
+
+TODO:
+
+- Help the reader understand the difference between Postgres and Mathesar. Help them understand that Postgres is only one of many different types of databases.
+- link to Postgres site
+- Explain that Mathesar works only with Postgres, and explain why
+- Explain the difference between "databases", "schemas", and "tables", making it clear when/why a user should choose a separate _database_ vs a separate _schema_.
+
+-->
+
+Mathesar provides a spreadsheet-like interface to a PostgreSQL database. Mathesar works by connection to an Postgres server using a database credentials with appropriate [permissions](#permissions) provided by you, inferring the database structure by reading through the [catalog tables](https://www.postgresql.org/docs/current/catalogs.html) which we call as reflection and presenting the reflected data in a easy to use UI. We also help the user modify, perform SQL operations using the UI by converting the actions done using to equivalent SQL command and running it on the Postgres database. 
+
+## PostgreSQL permissions {:#permissions}
+
+## Mathesar schemas {:#schemas}
+
+## Reflection {:#reflection}

docs/docs/index.md

@@ -4,6 +4,8 @@
 
 Mathesar is a self-hostable open source project that provides a spreadsheet-like interface to a PostgreSQL database. Our web-based interface helps you and your collaborators set up data models, edit data, and build custom reports — no technical skills needed. You can create a new PostgreSQL database while setting up Mathesar or use our UI to interact with an existing database (or do both).
 
+See our [conceptual overview](./concepts.md) to learn more about the inner workings of Mathesar.
+
 ## Try Mathesar
 
 Try our [live demo](https://demo.mathesar.org/) to try out Mathesar online.

docs/mkdocs.yml

@@ -6,6 +6,7 @@ repo_name: centerofci/mathesar
 nav:
   - Introduction:
       - Welcome: index.md
+      - Conceptual Overview: concepts.md
   - Installation:
       - Install using Docker image: installation/docker/index.md
       - Install using Docker Compose: installation/docker-compose/index.md