Make it clearer that the template dir is relative to synapse's root dir

changelog.d/5543.misc

@@ -0,0 +1 @@
+Make the config clearer in that email.template_dir is relative to the Synapse's root directory, not the `synapse/` folder within it.

docs/sample_config.yaml

@@ -1070,11 +1070,13 @@ password_config:
 # app_name: Matrix
 #
 # # Enable email notifications by default
+# #
 # notif_for_new_users: True
 #
 # # Defining a custom URL for Riot is only needed if email notifications
 # # should contain links to a self-hosted installation of Riot; when set
 # # the "app_name" setting is ignored
+# #
 # riot_base_url: "http://localhost/riot"
 #
 # # Enable sending password reset emails via the configured, trusted
@@ -1087,18 +1089,24 @@ password_config:
 # #
 # # If this option is set to false and SMTP options have not been
 # # configured, resetting user passwords via email will be disabled
+# #
 # #trust_identity_server_for_password_resets: false
 #
 # # Configure the time that a validation email or text message code
 # # will expire after sending
 # #
 # # This is currently used for password resets
+# #
 # #validation_token_lifetime: 1h
 #
 # # Template directory. All template files should be stored within this
 # # directory
 # #
-# #template_dir: res/templates
+# # If not set, the default location is `(location of Synapse's
+# # virtualenv)/res/templates`. Using an absolute path is recommended
+# # when changing this option from the default.
+# #
+# #template_dir: synapse-env/res/templates
 #
 # # Templates for email notifications
 # #

synapse/config/emailconfig.py

@@ -233,11 +233,13 @@ def default_config(self, config_dir_path, server_name, **kwargs):
  # app_name: Matrix
  #
  # # Enable email notifications by default
+ # #
  # notif_for_new_users: True
  #
  # # Defining a custom URL for Riot is only needed if email notifications
  # # should contain links to a self-hosted installation of Riot; when set
  # # the "app_name" setting is ignored
+ # #
  # riot_base_url: "http://localhost/riot"
  #
  # # Enable sending password reset emails via the configured, trusted
@@ -250,18 +252,24 @@ def default_config(self, config_dir_path, server_name, **kwargs):
  # #
  # # If this option is set to false and SMTP options have not been
  # # configured, resetting user passwords via email will be disabled
+ # #
  # #trust_identity_server_for_password_resets: false
  #
  # # Configure the time that a validation email or text message code
  # # will expire after sending
  # #
  # # This is currently used for password resets
+ # #
  # #validation_token_lifetime: 1h
  #
  # # Template directory. All template files should be stored within this
  # # directory
  # #
- # #template_dir: res/templates
+ # # If not set, the default location is `(location of Synapse's
+ # # virtualenv)/res/templates`. Using an absolute path is recommended
+ # # when changing this option from the default.
+ # #
+ # #template_dir: synapse-env/res/templates
  #
  # # Templates for email notifications
  # #