🚨 misc: change codeblock language from plaintext to txt

content/blog/shortcodes/index.ca.md

@@ -28,7 +28,7 @@ Per incloure un diagrama Mermaid a la teva publicació, cal fer dues coses:
 
 2. Utilitza el shortcode `mermaid()` per definir el teu diagrama. Per exemple:
 
-```plaintext
+```txt
 {%/* mermaid() */%}
 classDiagram
     class DistorsionsCognitives {

content/blog/shortcodes/index.es.md

@@ -28,7 +28,7 @@ Para incluir un diagrama Mermaid en tu publicación, sigue estos dos pasos:
 
 2. Usa el shortcode `mermaid()` para definir tu diagrama. Por ejemplo:
 
-```plaintext
+```txt
 {%/* mermaid() */%}
 classDiagram
     class DistorsionesCognitivas {

content/blog/shortcodes/index.md

@@ -28,7 +28,7 @@ To include a Mermaid diagram in your post, there are two steps:
 
 2. Use the `mermaid()` shortcode to define your diagram in your posts. For example:
 
-```plaintext
+```txt
 {%/* mermaid() */%}
 classDiagram
     class CognitiveDistortions {