fix: update key placeholders (#38)

src/features/settings/panels/KWMv2/KWMv2EKeyItem.tsx

@@ -53,7 +53,12 @@ export const KWMv2EKeyItem = memo(({ id, ekey, quality, rid, i }: StagingKWMv2Ke
             <InputLeftElement pr="2">
               <Icon as={MdVpnKey} />
             </InputLeftElement>
-            <Input variant="flushed" placeholder="密钥" value={ekey} onChange={(e) => updateKey('ekey', e)} />
+            <Input
+              variant="flushed"
+              placeholder="密钥，通常包含 364 或 704 位字符，没有空格。"
+              value={ekey}
+              onChange={(e) => updateKey('ekey', e)}
+            />
             <InputRightElement>
               <Text pl="2" color={ekey.length ? 'green.500' : 'red.500'}>
                 <code>{ekey.length || '?'}</code>