message: Update common-plugins.md
  common-plugins(gh-page): add link to autopopulate
  common-plugins(gh-page): add notice on population depth
  This is a squash merge of typegoose/typegoose#261
diff: @@ -6,7 +6,7 @@ Typegoose supports mongoose plugins. Here's how to use some common plugins:
  ## mongoose-autopopulate
  -Typegoose has the PropOption `autopopulate` implemented, but it only has an effect if `mongoose-autopopulate` is used too.
  +Typegoose has the PropOption `autopopulate` implemented, but it only has an effect if [`mongoose-autopopulate`](https://github.com/mongodb-js/mongoose-autopopulate) is used too.
  ```ts
  import * as mongoose from "mongoose";
  @@ -37,6 +37,16 @@ const SomeReferencedClassModel = getModelForClass(SomeReferencedClass);
  ```
  +**PLEASE NOTE:** If you have a 'ref' which refers back to its own class/ model, like having a User class with a `createdBy` field referring back to User, then you'll need to set the `maxDepth` prop of `autocomplete` to 1. If you don't do this, Mongoose will do recursive call to the user collection 10 times, extremely delaying the output of the query. Below is an example of how to set `maxDepth`.
  +
  +```
  +@plugin(autopopulate as any) // this is an dirty fix, because the types of this plugin dont work
  +class SomeClass {
  + @prop({ autopopulate: { maxDepth: 1 }, ref: "SomeReferencedClass" })
  + public populateField: Ref<SomeReferencedClass>;
  +}
  +```
  +
  ## mongoose-findorcreate
  Typegoose has a default class for `mongoose-findorcreate` that has all the types it needs. Here's how to use it:
  