Add basic documentation

docs/Project.toml

@@ -3,7 +3,10 @@
 #     pkg> dev ..
 #
 [deps]
+CSV = "336ed68f-0bac-5ca0-87d4-7b16caf5d00b"
+DataFrames = "a93c6f00-e57d-5684-b7b6-d8193f3e46c0"
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+DuckDB = "d2f5444f-75bc-4fdf-ac35-56f514c445e1"
 
 [compat]
 Documenter = "1"

docs/src/index.md

@@ -4,4 +4,36 @@ CurrentModule = TulipaIO
 
 # TulipaIO
 
-Documentation for [TulipaIO](https://github.com/TulipaEnergy/TulipaIO.jl).
+[TulipaIO](https://github.com/TulipaEnergy/TulipaIO.jl) is part of the Tulipa ecosystem of packages.
+The main package in this ecosystem is [TulipaEnergyModel.jl](https://tulipaenergy.github.io/TulipaEnergyModel.jl/stable/).
+Check that package first for more information on the ecosystem.
+
+## Usage
+
+TulipaIO is used to provide input to TulipaEnergyModel and other packages in the ecosystem.
+Here is some basic usage:
+
+First, we read a fake CSV file with the relevant information.
+
+```@example basic
+using TulipaIO: TulipaIO
+using DuckDB: DBInterface, DB
+
+con = DBInterface.connect(DB)
+filepath = joinpath(@__DIR__, "..", "..", "test", "data", "Norse", "assets-data.csv") #hide
+table_name = TulipaIO.create_tbl(con, filepath) # filepath is the path to a CSV
+```
+
+Then we can run SQL commands using the DuckDB interface.
+It returns a `DuckDB.QueryResult`, which we convert to Dict to visualize:
+
+```@example basic
+DBInterface.execute(con, "SELECT name, variable_cost FROM $table_name WHERE type = 'conversion'") |> Dict
+```
+
+This allows simple conversion to DataFrame as well:
+
+```@example basic
+using DataFrames: DataFrame
+DataFrame(DBInterface.execute(con, "SELECT name, type, investable, variable_cost FROM $table_name WHERE name LIKE 'Asgard_%'"))
+```