Docs: add extras to installation docs page (#1370)

* Add extras to installation docs page

* format table

---------

Co-authored-by: eakmanrq <6326532+eakmanrq@users.noreply.github.com>

Author: treysp

docs/installation.md

@@ -1,19 +1,55 @@
 # Installation
 
+## Python virtual environment
 
-It is recommended, but not required, that you use a python virtual environment:
+It is recommended, but not required, that you use a python virtual environment with SQLMesh.
+
+First, create the virtual environment:
 ```bash
 python -m venv .env
 ```
+
+Then activate it:
 ```bash
 source .env/bin/activate
 ```
 
-Install SQLMesh using `pip`:
+## Install SQLMesh core
+
+Install the core SQLMesh library with `pip`:
 ```bash
 pip install sqlmesh
 ```
 
+## Install extras
+Some SQLMesh functionality requires additional Python libraries. `pip` will automatically install them for you if you specify the relevant name in brackets.
+
+Some extras add features:
+
+| Feature             | `pip` command                   |
+|---------------------|---------------------------------|
+| Browser UI          | `pip install "sqlmesh[web]"`    |
+| dbt projects        | `pip install "sqlmesh[dbt]"`    |
+| Github CI/CD bot    | `pip install "sqlmesh[github]"` |
+| Slack notifications | `pip install "sqlmesh[slack]"`  |
+| Development setup   | `pip install "sqlmesh[dev]"`    |
+| LLM SQL prompt      | `pip install "sqlmesh[llm]"`    |
+
+Other extras are required to use specific SQL engines:
+
+| SQL engine    | `pip` command                        |
+|---------------|--------------------------------------|
+| Bigquery      | `pip install "sqlmesh[bigquery]"`    |
+| Databricks    | `pip install "sqlmesh[databricks]"`  |
+| GCP Postgres  | `pip install "sqlmesh[gcppostgres]"` |
+| MS SQL Server | `pip install "sqlmesh[mssql]"`       |
+| MySQL         | `pip install "sqlmesh[mysql]"`       |
+| Postgres      | `pip install "sqlmesh[postgres]"`    |
+| Redshift      | `pip install "sqlmesh[redshift]"`    |
+| Snowflake     | `pip install "sqlmesh[snowflake]"`   |
+
+Multiple extras can be installed at once, as in `pip install "sqlmesh[web,slack]"`.
+
 ## Next steps
 * Jump right in with the [quickstart example project](quick_start.md).
-* Have an existing dbt project? [Check out SQLMesh's dbt adapter](./integrations/dbt.md).
+* Have an existing dbt project? Install the dbt extra and [check out SQLMesh's dbt adapter](./integrations/dbt.md).