Create a single README.md file in spec/ (bugs 13084, 13085)

spec/input/README.md → spec/README.md

+reference-repository specs
+==========================
+
+This directory contains a test suite for the ref-repo OAR properties generator.
+
+The tests are split into different files:
+- `oar_properties_arguments_spec.rb` contains basic tests for all arguments passed to the generator
+- `oar_properties_spec.rb` contains various fictious tests
+- `oar_properties2_spec.rb` contains various tests based on real data
+
+Both `oar_properties_spec.rb` and `oar_properties2_spec.rb` rely on a
+`check_oar_properties` method that uses input files from `input`, and
+compares the generated results to files in `output`.
+For example, `check_oar_properties({ :oar => 'oar_empty', :data => 'data', :case => 'empty' })`
+will use `input/oar_empty.json` and `input/data.json`, and compare the results
+to `output/empty_{print,diff,table}_*.json`.
+
 How to update input files:
 ==========================
 
@@ -18,3 +35,9 @@ Steps are:
 Since using `vimdiff` or `meld` on the files is very slow, one can use the `diff` and `patch` commands...
 
 Then verify using `git diff` that the generated data matches what you expect.
+
+How to update the output files:
+===============================
+
+To update the files, just remove them and run rspec again, they will be regenerated.
+Then verify using `git diff` that the generated data matches what you expect.

spec/output/README.md

-How to update the output files:
-===============================
-
-To update the files, just remove them and run rspec again, they will be regenerated.
-Then verify using `git diff` that the generated data matches what you expect.