Add documentation on running RegistryCI on a registry.

README.md

@@ -133,3 +133,4 @@ will look for a package in the current directory.
 * [Migrating Packages from the General Registry](docs/migration_from_general.md)
 * [Using LocalRegistry on a Shared Filesysem](docs/shared_filesystem.md)
 * [Delete a Registered Package](docs/delete_package.md)
+* [Registry Consistency Testing](docs/registry_ci.md)

docs/registry_ci.md

@@ -0,0 +1,41 @@
+# Registry Consistency Testing
+
+For trouble-shooting, or as good practice if you have your registry
+set up with CI (Continuous Integration), you can run the registry
+consistency tests from the
+[RegistryCI](https://github.com/JuliaRegistries/RegistryCI.jl)
+package on your registry.
+
+In the following sections it is assumed that all packages in your
+registry have all their dependencies registerad either in your own
+registry or in the General registry, which is the typical scenario.
+
+## Manual Testing
+
+Add RegistryCI
+```
+pkg> add RegistryCI
+```
+and run the consistency tests:
+```
+using RegistryCI
+withenv("JULIA_PKG_UNPACK_REGISTRY" => "true") do
+    RegistryCI.test(path_to_your_registry, registry_deps = ["General"])
+end
+```
+
+## CI Testing
+
+The idea is the same as for manual testing. A sample GitLab CI job for
+your registry repository can look something like:
+```
+registry consistency test:
+  stage: test
+  variables:
+    JULIA_PKG_UNPACK_REGISTRY: "true"
+  script:
+    - git config --global user.name $GITLAB_USER_NAME
+    - git config --global user.email $GITLAB_USER_EMAIL
+    - julia -e 'using Pkg; Pkg.add("RegistryCI")'
+    - julia --color=yes -e 'using RegistryCI; RegistryCI.test(@__DIR__, registry_deps = ["General"])'
+```