fix(keyboard): extra padding in special character and numlock drawers

Also adds a (slightly modified for better flow) description for the Compose key from designs.

i18n/en/cosmic_settings.ftl

@@ -574,6 +574,7 @@ keyboard-sources = Input Sources
 keyboard-special-char = Special Character Entry
     .alternate = Alternate characters key
     .compose = Compose key
+    .compose-desc = The compose key allows a wide variety of characters to be entered. To use it, press compose and then a sequence of characters. For example, compose key followed by C and o will enter ©, while compose key followed by a and ‘ will enter á.
     .caps = Caps Lock key
 
 keyboard-typing-assist = Typing

i18n/sr-Cyrl/cosmic_settings.ftl

@@ -513,6 +513,7 @@ keyboard-sources = Језик уноса
 keyboard-special-char = Уношење специјалних знакова
     .alternate = Тастер за алтернативне знакове
     .compose = Compose тастер
+    .compose-desc = Compose тастер омогућава унос широког спектра знакова. Да бисте га користили, притисните Compose, а затим секвенцу знакова. На пример, Compose тастер праћен тастерима C и o уноси ©, док праћен тастерима а и ‘ уноси á.
     .caps = Caps Lock тастер
 keyboard-typing-assist = Куцање
     .repeat-rate = Стопа понављања

i18n/sr-Latn/cosmic_settings.ftl

@@ -513,6 +513,7 @@ keyboard-sources = Jezik unosa
 keyboard-special-char = Unošenje specijalnih znakova
     .alternate = Taster za alternativne znakove
     .compose = Compose taster
+    .compose-desc = Compose taster omogućava unos širokog spektra znakova. Da biste ga koristili, pritisnite Compose, a zatim sekvencu znakova. Na primer, Compose taster praćen tasterima C i o unosi ©, dok praćen tasterima a i ‘ unosi á.
     .caps = Caps Lock taster
 keyboard-typing-assist = Kucanje
     .repeat-rate = Stopa ponavljanja