scalafmt: add page (#6808)

pages/common/scalafmt.md

@@ -0,0 +1,25 @@
+# scalafmt
+
+> Code formatter for Scala.
+> Configurations are stored in the `.scalafmt.conf` file.
+> More information: <https://scalameta.org/scalafmt>.
+
+- Reformat all `.scala` files in the current directory recursively:
+
+`scalafmt`
+
+- Reformat specific files or directories with a custom formatting configuration:
+
+`scalafmt --config {{path/to/.scalafmt.conf}} {{path/to/file_or_directory}} {{path/to/file_or_directory}} {{...}}`
+
+- Check if files are correctly formatted, returning `0` if all files respect the formatting style:
+
+`scalafmt --config {{path/to/.scalafmt.conf}} --test`
+
+- Exclude files or directories:
+
+`scalafmt --exclude {{path/to/file_or_directory}} {{...}}`
+
+- Format only files that were edited against the current Git branch:
+
+`scalafmt --config {{path/to/.scalafmt.conf}} --mode diff`