docs: add io to fmt.md

Signed-off-by: Gabor Boros <gabor.brs@gmail.com>

Author: gabor-boros

api/java/string-manipulation/fmt.md

@@ -3,6 +3,9 @@ layout: api-command
 language: Java
 permalink: api/java/fmt/
 command: fmt
+io:
+    -   - r
+        - string
 related_commands:
     match: match/
     split: split/

api/javascript/string-manipulation/fmt.md

@@ -3,6 +3,9 @@ layout: api-command
 language: JavaScript
 permalink: api/javascript/fmt/
 command: fmt
+io:
+    -   - r
+        - string
 related_commands:
     match: match/
     split: split/

api/python/string-manipulation/fmt.md

@@ -3,6 +3,9 @@ layout: api-command
 language: Python
 permalink: api/python/fmt/
 command: fmt
+io:
+    -   - r
+        - string
 related_commands:
     match: match/
     split: split/

api/ruby/string-manipulation/fmt.md

@@ -3,6 +3,9 @@ layout: api-command
 language: Ruby
 permalink: api/ruby/fmt/
 command: fmt
+io:
+    -   - r
+        - string
 related_commands:
     match: match/
     split: split/