docs(minerr): fill in error message descriptions

Errors I've documented so far:
- `$injector:cdep`
- `$injector:itkn`
- `$injector:modulerr`
- `$injector:nomod`
- `$injector:pget`
- `$injector:unpr`
- `ng:areq`
- `ng:cpi`
- `ng:cpws`
- `ngModel:noass`

Closes #3430

1 files changed, 22 insertions, 0 deletions

diff --git a/docs/content/error/injector/cdep.ngdoc b/docs/content/error/injector/cdep.ngdoc
index f4a9c909..0e9769c4 100644
--- a/docs/content/error/injector/cdep.ngdoc
+++ b/docs/content/error/injector/cdep.ngdoc
@@ -2,3 +2,25 @@
 @name $injector:cdep
 @fullName Circular Dependency
 @description
+
+This error occurs when the {@link api/angular.injector $injector} tries to get
+a service that depends on itself, either directly or indirectly. To fix this,
+construct your dependency chain such that there are no circular dependencies.
+
+For example:
+
+```
+angular.module('myApp', [])
+  .factory('myService', function (myService) {
+    // ...
+  })
+  .controller('MyCtrl', function ($scope, myService) {
+    // ...
+  });
+```
+
+When an instance of `MyCtrl` is created, the service `myService` will be created
+by the `$injector`. `myService` depends on itself, which causes the `$injector`
+to detect a circular dependency and throw the error.
+
+For more information, see the {@link guide/di Dependency Injection Guide}.
\ No newline at end of file