Add documentation to every function and automatic doc html building (#6)

Reviewed-on: Rubydragon/MetagraphOptimization.jl#6
Co-authored-by: Anton Reinhard <anton.reinhard@proton.me>
Co-committed-by: Anton Reinhard <anton.reinhard@proton.me>

src/task/create.jl

@@ -0,0 +1,14 @@
+"""
+    copy(t::AbstractDataTask)
+
+Fallback implementation of the copy of an abstract data task, throwing an error.
+"""
+copy(t::AbstractDataTask) =
+    error("Need to implement copying for your data tasks!")
+
+"""
+    copy(t::AbstractComputeTask)
+
+Return a copy of the given compute task.
+"""
+copy(t::AbstractComputeTask) = typeof(t)()