Fix backticks usage in README

README.md

@@ -285,7 +285,7 @@ take precedence over the contents of an `.env` file.**
 - [`NAP_START_MIN`](#nap_start_min)
 - [`DB_ENGINE`](#db_engine)
 - [`DB_HOST`](#db_host)
-- ['DB_NAME'](#db_name)
+- [`DB_NAME`](#db_name)
 - [`DB_PASSWORD`](#db_password)
 - [`DB_PORT`](#db_port)
 - [`DB_USER`](#db_user)
@@ -360,7 +360,7 @@ entry is consider a nap. Expects the 24-hour format %H:%M.
 The minimum *start* time (in the instance's time zone) after which a sleep
 entry is considered a nap. Expects the 24-hour format %H:%M.
 
-### 'DB_ENGINE'
+### `DB_ENGINE`
 
 *Default: django.db.backends.postgresql*
 
@@ -368,31 +368,31 @@ The database engine utilized for the deployment.
 
 See also [Django's documentation on the ENGINE setting](https://docs.djangoproject.com/en/3.0/ref/settings/#engine) .
 
-### 'DB_HOST'
+### `DB_HOST`
 
 *Default: db*
 
 The name of the database host for the deployment.
 
-### 'DB_NAME'
+### `DB_NAME`
 
 *Default: postgres*
 
 The name of the database table utilized for the deployment.
 
-### 'DB_PASSWORD'
+### `DB_PASSWORD`
 
 *No Default*
 
 The password for the database user for the deployment. In the default example, this is the root PostgreSQL password.
 
-### 'DB_PORT'
+### `DB_PORT`
 
 *Default: 5432*
 
 The listening port for the database. The default port is 5432 for PostgreSQL.
 
-### 'DB_USER'
+### `DB_USER`
 
 *Default: postgres*