shfmt: add page (#10113)

Co-authored-by: CleanMachine1 <78213164+CleanMachine1@users.noreply.github.com>
Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/shfmt.md

@@ -0,0 +1,20 @@
+# shfmt
+
+> Shell parser, formatter and interpreter.
+> More information: <https://pkg.go.dev/mvdan.cc/sh>.
+
+- Print a formatted version of a shell script:
+
+`shfmt {{path/to/file}}`
+
+- List unformatted files:
+
+`shfmt --list {{path/to/directory}}`
+
+- Write the result to the file instead of printing it to the terminal:
+
+`shfmt --write {{path/to/file}}`
+
+- Simplify the code, removing redundant pieces of syntax (i.e. removing "$" from vars in expressions):
+
+`shfmt --simplify {{path/to/file}}`