Simplify

No need to define `mypackage_dir` anymore, it was only needed in an earlier
iteration of my experiments.

Author: giordano

docs/src/advanced.md

@@ -1,8 +1,7 @@
 ```@setup mypackage
 using ParallelTestRunner
-mypackage_dir = joinpath(pkgdir(ParallelTestRunner), "docs", "MyPackage")
 using MyPackage
-test_dir = joinpath(mypackage_dir, "test")
+test_dir = joinpath(pkgdir(ParallelTestRunner), "docs", "MyPackage", "test")
 ```
 
 # Advanced Usage

docs/src/index.md

@@ -9,9 +9,8 @@ end
 
 ```@setup mypackage
 using ParallelTestRunner
-mypackage_dir = joinpath(pkgdir(ParallelTestRunner), "docs", "MyPackage")
 using MyPackage
-test_dir = joinpath(mypackage_dir, "test")
+test_dir = joinpath(pkgdir(ParallelTestRunner), "docs", "MyPackage", "test")
 ```
 
 [ParallelTestRunner.jl](https://github.com/JuliaTesting/ParallelTestRunner.jl) is a simple parallel test runner for Julia tests with automatic test discovery.