Update docs for Element Web and SchildiChat Web: add the instruction to change the default country code to help to make the clients less British

Note the order of the instructions is intended to align with that of configurations on main.yml files.

Also: replace the explanations with the one available at https://github.com/element-hq/element-web/blob/develop/docs/config.md

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/configuring-playbook-client-element-web.md

@@ -17,11 +17,19 @@ When setting, replace `example.com` with your own.
 
 ## Adjusting the playbook configuration
 
+### Set the country code for phone number inputs
+
+You can change the country code (default: `GB`) to use when showing phone number inputs. To change it to `FR` for example, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
+
+```yaml
+matrix_client_element_default_country_code: "FR"
+```
+
 ### Themes
 
 #### Change the default theme
 
-You can change the default theme from `light` to `dark`. To do so, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
+You can change the default theme from `light` to `dark`. To do so, add the following configuration to your `vars.yml` file:
 
 ```yaml
 # Controls the default theme

docs/configuring-playbook-client-schildichat-web.md

@@ -22,11 +22,19 @@ To enable SchildiChat Web, add the following configuration to your `inventory/ho
 matrix_client_schildichat_enabled: true
 ```
 
+### Set the country code for phone number inputs
+
+You can change the country code (default: `GB`) to use when showing phone number inputs. To change it to `FR` for example, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
+
+```yaml
+matrix_client_schildichat_default_country_code: "FR"
+```
+
 ### Themes
 
 #### Change the default theme
 
-You can change the default theme from `light` to `dark`. To do so, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
+You can change the default theme from `light` to `dark`. To do so, add the following configuration to your `vars.yml` file:
 
 ```yaml
 # Controls the default theme

roles/custom/matrix-client-element/defaults/main.yml

@@ -194,7 +194,7 @@ matrix_client_element_self_check_validate_certificates: true
 # don't show the registration button on welcome page
 matrix_client_element_registration_enabled: false
 
-# Default country code on welcome page when login by phone number
+# An optional ISO 3166 alpha2 country code (eg: GB, the default) to use when showing phone number inputs
 matrix_client_element_default_country_code: "GB"
 
 # Controls whether presence will be enabled

roles/custom/matrix-client-schildichat/defaults/main.yml

@@ -189,7 +189,7 @@ matrix_client_schildichat_self_check_validate_certificates: true
 # don't show the registration button on welcome page
 matrix_client_schildichat_registration_enabled: false
 
-# Default country code on welcome page when login by phone number
+# An optional ISO 3166 alpha2 country code (eg: GB, the default) to use when showing phone number inputs
 matrix_client_schildichat_default_country_code: "GB"
 
 # Controls whether presence will be enabled