Fix accidentally-escaped newlines in ABC music demo (#1004)

Author: WebCoder49

website/en/book/elements/abc-music.md

@@ -26,7 +26,9 @@ K: Emin
 X:1
 T: Cooley's Long
 M: 4/4
-L: 1/8\nR: reel\nK: Emin
+L: 1/8
+R: reel
+K: Emin
 D2|:"Em"EB{c}BA B2 EB|~B2 AB dBAG|"D"FDAD BDAD|FDAD dAFD|
 "Em"EBBA B2 EB|B2 AB defg|"D"afe^c dBAF|1"Em"DEFD E2 D2:|2"Em"DEFD E2 gf||
 |:"Em"eB B2 efge|eB B2 gedB|"D"A2 FA DAFA|A2 FA defg|
@@ -47,9 +49,11 @@ K: Emin
 X:1
 T: Cooley's Long
 M: 4/4
-L: 1/8\nR: reel\nK: Emin
+L: 1/8
+R: reel
+K: Emin
 D2|:"Em"EB{c}BA B2 EB|~B2 AB dBAG|"D"FDAD BDAD|FDAD dAFD|
 "Em"EBBA B2 EB|B2 AB defg|"D"afe^c dBAF|1"Em"DEFD E2 D2:|2"Em"DEFD E2 gf||
 |:"Em"eB B2 efge|eB B2 gedB|"D"A2 FA DAFA|A2 FA defg|
 "Em"eB B2 eBgB|eB B2 defg|"D"afe^c dBAF|1"Em"DEFD E2 gf:|2"Em"DEFD E4|]
-```
+```