git-hash-object: add page

pages/common/git-hash-object.md

@@ -0,0 +1,20 @@
+# git hash-object
+
+> Computes the unique hash key of content and optionally creates an object with specified type.
+> More information: <https://git-scm.com/docs/git-hash-object>.
+
+- Compute the ID that would be used to store it in git database:
+
+`git hash-object {{/path/to/file}}`
+
+- Compute the ID and store it in git database:
+
+`git hash-object -w {{/path/to/file}}`
+
+- Compute the ID and specify the type of object:
+
+`git hash-object -t {blob | tree | commit | tag} {{/path/to/file}}`
+
+- Compute the ID from user input instead of a file:
+
+`git hash-object --stdin`