Move submodules with specifications to "spec" directory

Author: shorodilov

.gitmodules

@@ -2,10 +2,10 @@
 path = problem-sets
 url = git@github.com:edu-python-course/problem-sets
 [submodule "src/appx/blog"]
-path = src/appx/blog
+path = src/spec/blog
 url = git@github.com:edu-python-course/blog-spec
 [submodule "src/appx/libms"]
-path = src/appx/libms
+path = src/spec/libms
 url = git@github.com:edu-python-course/libms-spec.git
 [submodule "src/spec/giver"]
 path = src/spec/giver