add docs to readme until GH pages successfully deployed

Author: ablaom

README.md

@@ -19,3 +19,67 @@ to [MLJBase.jl](https://github.com/JuliaAI/MLJBase.jl) which do not
 appear in the commit history of this repository.
 
 Package documentation is [here](https://JuliaAI.github.io/OpenML.jl/dev).
+
+## Summary of functionality
+
+- `OpenML.list_tags()`: for listing all dataset tags
+        
+- `OpenML.list_datasets(; tag=nothing, filter=nothing, output_format=...)`: for listing available datasets
+
+- `OpenML.describe_dataset(id)`: to describe a particular dataset
+
+- `OpenML.load(id; parser=:arff)`: to download a dataset
+
+
+## Installation
+
+```julia
+using Pkg
+Pkg.add("OpenML")
+```
+
+If running the demonstration below:
+
+```julia
+Pkg.add("DataFrames") 
+Pkg.add("ScientificTypes")
+```
+
+## Sample usage
+
+```julia
+using OpenML # or using MLJ
+using DataFrames
+
+OpenML.list_tags()
+```
+
+Listing all datasets with the "OpenML100" tag which also have `n`
+instances and `p` features, where `100 < n < 1000` and `1 < p < 10`:
+
+```julia
+ds = OpenML.list_datasets(
+          tag = "OpenML100",
+          filter = "number_instances/100..1000/number_features/1..10",
+          output_format = DataFrame)
+```
+
+Describing and loading one of these datasets:
+
+```julia
+OpenML.describe_dataset(15)
+table = OpenML.load(15)
+```
+
+Converting to a data frame:
+
+```julia
+df = DataFrame(table)
+```
+
+Inspecting it's schema:
+
+```julia
+using ScientificTypes
+schema(table)
+```