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/osx/cat.md

@@ -3,7 +3,7 @@
 > Print and concatenate files.
 > More information: <https://keith.github.io/xcode-man-pages/cat.1.html>.
 
-- Print the contents of a file to the standard output:
+- Print the contents of a file to `stdout`:
 
 `cat {{path/to/file}}`
 

pages/osx/dmesg.md

@@ -1,6 +1,6 @@
 # dmesg
 
-> Write the kernel messages to standard output.
+> Write the kernel messages to `stdout`.
 > More information: <https://www.manpagez.com/man/8/dmesg/>.
 
 - Show kernel messages:

pages/osx/pbpaste.md

@@ -1,6 +1,6 @@
 # pbpaste
 
-> Send the contents of the clipboard to standard output.
+> Send the contents of the clipboard to `stdout`.
 > Comparable to pressing Cmd + V on the keyboard.
 > More information: <https://ss64.com/osx/pbpaste.html>.
 

pages/osx/wc.md

@@ -19,6 +19,6 @@
 
 `wc -m {{path/to/file}}`
 
-- Use standard input to count lines, words and characters (bytes) in that order:
+- Use `stdin` to count lines, words and characters (bytes) in that order:
 
 `{{find .}} | wc`