Merge deploy keys example to deploy keys API docs

No reason to keep them separate.

doc/api/deploy_key_multiple_projects.md

-# Adding deploy keys to multiple projects via API
+---
+redirect_to: deploy_keys.md#adding-deploy-keys-to-multiple-projects
+---
 
-If you want to easily add the same deploy key to multiple projects in the same
-group, this can be achieved quite easily with the API.
-
-First, find the ID of the projects you're interested in, by either listing all
-projects:
-
-```
-curl --header 'PRIVATE-TOKEN: <your_access_token>' https://gitlab.example.com/api/v4/projects
-```
-
-Or finding the ID of a group and then listing all projects in that group:
-
-```
-curl --header 'PRIVATE-TOKEN: <your_access_token>' https://gitlab.example.com/api/v4/groups
-
-# For group 1234:
-curl --header 'PRIVATE-TOKEN: <your_access_token>' https://gitlab.example.com/api/v4/groups/1234
-```
-
-With those IDs, add the same deploy key to all:
-
-```
-for project_id in 321 456 987; do
-    curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" --header "Content-Type: application/json" \
-    --data '{"title": "my key", "key": "ssh-rsa AAAA..."}' https://gitlab.example.com/api/v4/projects/${project_id}/deploy_keys
-done
-```
+This document was moved to [another location](deploy_keys.md#adding-deploy-keys-to-multiple-projects).

doc/api/deploy_keys.md

@@ -203,3 +203,32 @@ Example response:
    "created_at" : "2015-08-29T12:44:31.550Z"
 }
 ```
+## Adding deploy keys to multiple projects
+
+If you want to easily add the same deploy key to multiple projects in the same
+group, this can be achieved quite easily with the API.
+
+First, find the ID of the projects you're interested in, by either listing all
+projects:
+
+```
+curl --header 'PRIVATE-TOKEN: <your_access_token>' https://gitlab.example.com/api/v4/projects
+```
+
+Or finding the ID of a group and then listing all projects in that group:
+
+```
+curl --header 'PRIVATE-TOKEN: <your_access_token>' https://gitlab.example.com/api/v4/groups
+
+# For group 1234:
+curl --header 'PRIVATE-TOKEN: <your_access_token>' https://gitlab.example.com/api/v4/groups/1234
+```
+
+With those IDs, add the same deploy key to all:
+
+```
+for project_id in 321 456 987; do
+    curl --request POST --header "PRIVATE-TOKEN: <your_access_token>" --header "Content-Type: application/json" \
+    --data '{"title": "my key", "key": "ssh-rsa AAAA..."}' https://gitlab.example.com/api/v4/projects/${project_id}/deploy_keys
+done
+```