fmt: add page

pages/common/fmt.md

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+# fmt
+
+> Reformat a text file by joining its paragraphs and limiting the line width to given number of characters (75 by default).
+
+- Reformat a file:
+
+`fmt {{path/to/file}}`
+
+- Reformat a file producing output lines of (at most) `n` characters:
+
+`fmt -w {{n}} {{path/to/file}}`
+
+- Reformat a file without joining lines shorter than the given width together:
+
+`fmt -s {{path/to/file}}`
+
+- Reformat a file with uniform spacing (1 space between words and 2 spaces between paragraphs):
+
+`fmt -u {{path/to/file}}`