docs(readme): slightly improve.
build(nuspec): add xunit.extensions.dll to files section

not to reference xunit.extensions.dll directly when the nuget package
is installed.
build(nuspec): add assemblies of autofixture to files section

not to depend on xunit.extensions when the nuget package is installed.
build(nuspec): add xunit.extensions nuget dependency,

to Experiment.AutoFixtureWithExample.nuspec.
docs(readme): add information about nuget packages

and its dependencies.
Merge branch 'optimize-references'
build(DEPLOYMENT): increment patch version,

to indicate that it is a fix to prevent xunit.extensions.dll from
being directly added to references.