git-var: add page (#5095)

* git-var: add page

* Update pages/common/git-var.md

Co-authored-by: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>

* Update pages/common/git-var.md

Co-authored-by: Axel Navarro <navarroaxel@gmail.com>

* Update git-var.md

Co-authored-by: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>
Co-authored-by: Axel Navarro <navarroaxel@gmail.com>

pages/common/git-var.md

@@ -0,0 +1,13 @@
+# git var
+
+> Prints a Git logical variable's value.
+> See `git config`, which is preferred over `git var`.
+> More information: <https://git-scm.com/docs/git-var>.
+
+- Print the value of a Git logical variable:
+
+`git var {{GIT_AUTHOR_IDENT|GIT_COMMITTER_IDENT|GIT_EDITOR|GIT_PAGER}}`
+
+- [l]ist all Git logical variables:
+
+`git var -l`