Wordings : Enhancement of background and UI color change thanks to better title and description

Signed-off-by: Jérôme Herbinet <33763786+Jerome-Herbinet@users.noreply.github.com>

Wordings : Now also talking about UI colour change possibility (and better explanation)

Signed-off-by: Jérôme Herbinet <33763786+Jerome-Herbinet@users.noreply.github.com>

npm run build

Signed-off-by: Jérôme Herbinet <33763786+Jerome-Herbinet@users.noreply.github.com>

Small additionnal change

Signed-off-by: Jérôme Herbinet <33763786+Jerome-Herbinet@users.noreply.github.com>

npm run build

Signed-off-by: Jérôme Herbinet <33763786+Jerome-Herbinet@users.noreply.github.com>

Following skjnldsv's review

... and adding [ by clicking on "Custom background" ] after "from your own files".

Signed-off-by: Jérôme Herbinet <33763786+Jerome-Herbinet@users.noreply.github.com>

Author: Jerome-Herbinet

apps/theming/src/UserThemes.vue

@@ -62,14 +62,14 @@
 			</NcCheckboxRadioSwitch>
 		</NcSettingsSection>
 
-		<NcSettingsSection :title="t('theming', 'Background')"
+		<NcSettingsSection :title="t('theming', 'Background and user interface color')"
 			class="background"
 			data-user-theming-background-disabled>
 			<template v-if="isUserThemingDisabled">
 				<p>{{ t('theming', 'Customization has been disabled by your administrator') }}</p>
 			</template>
 			<template v-else>
-				<p>{{ t('theming', 'Set a custom background') }}</p>
+				<p>{{ t('theming', 'Below, you can customize the background of your user interface, either with an image (from among those offered by default, or from your own files by clicking on "Custom background") or with a plain colour (by selecting the "No background" option and then clicking on "Change colour" if necessary). When you choose a background image, the system will adapt the colour of the interface (which will have an impact on folder icons, for example). If this colour doesn\'t suit you, you can pick another one by clicking on "Change colour".') }}</p>
 				<BackgroundSettings class="background__grid" @update:background="refreshGlobalStyles" />
 			</template>
 		</NcSettingsSection>