Add XML documentation (#10)

The prior `///` F# documentation blocks were not rendering in IDEs, and parameters were not documented. This change adds complete XML documentation to all (but `Compat`) classes, methods, and functions.

Reviewed-on: #10

src/Sqlite/BitBadger.Documents.Sqlite.fsproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <Description>Use SQLite as a document database</Description>
     <PackageTags>JSON Document SQLite</PackageTags>
+    <DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
   </PropertyGroup>
 
   <ItemGroup>