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/gnomon.md

@@ -3,7 +3,7 @@
 > Utility to annotate console logging statements with timestamps and find slow processes.
 > More information: <https://github.com/paypal/gnomon>.
 
-- Use UNIX (or DOS) pipes to pipe the `stdout` of any command through gnomon:
+- Use UNIX (or DOS) pipes to pipe `stdout` of any command through gnomon:
 
 `{{npm test}} | gnomon`