pages/*: add backticks around I/O streams (#10436)

* as suggested in #10428
* standard input  => `stdin`
* standard output => `stdout`
* standard error  => `stderr`

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/git-bundle.md

@@ -23,7 +23,7 @@
 
 `git bundle verify {{path/to/file.bundle}}`
 
-- Print to the standard output the list of references contained in a bundle:
+- Print to `stdout` the list of references contained in a bundle:
 
 `git bundle unbundle {{path/to/file.bundle}}`