Issue type:

[ ] question
[ ] bug report
[x] feature request
[ ] documentation issue

Database system/driver:

[ ] cordova
[ ] mongodb
[ ] mssql
[ ] mysql / mariadb
[ ] oracle
[x] postgres
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo

TypeORM version:

[x] latest
[ ] @next
[ ] 0.x.x (or put your version here)

Feature request:
When I define my entities I would like to be able to set a COMMENT to the database object. From looking at the source code this seems to be currently possible only for MySQL and not for PostgreSQL:

@Entity()
export class User {
  ...
  @Column({comment: 'The age in years.'})  // <--
  age: number
}

Using PostgreSQL one can also set a COMMENT on the table itself, which is not yet supported by TypeORM at all, but could look like this:

@Entity({comment: 'A user profile in the wep app.'})  // <--
export class User {
  ...
  @Column({comment: 'The age in years.'})
  age: number
}

I am asking for this feature as I am using the awesome PostGraphile tool, which heavily relies on COMMENTs for its configuration, and it would be really useful to do this by using TypeORM entity decorators!!

Many thanks,
Ulrich