Add DB_SSLMODE to config page (#812)

* Add DB_SSLMODE to config page

* Add DB_SSLMODE for zh-cn

content/en/admin/config.md

@@ -189,6 +189,10 @@ Defaults to `5432`.
 
 How many database connections to pool in the process. This value should cover every thread in the process, for this reason, it defaults to the value of `MAX_THREADS`.
 
+#### `DB_SSLMODE`
+
+Postgres's [SSL mode](https://www.postgresql.org/docs/10/libpq-ssl.html). Defaults to `prefer`.
+
 #### `DATABASE_URL`
 
 If provided, takes precedence over `DB_HOST`, `DB_USER`, `DB_NAME`, `DB_PASS` and `DB_PORT`.

content/zh-cn/admin/config.md

@@ -78,6 +78,7 @@ Mastodon使用环境变量作为其的配置。
 * `DB_NAME`
 * `DB_PASS`
 * `DB_PORT`
+* `DB_SSLMODE`
 * `DATABASE_URL`
 
 ### Redis {#redis}