pages*: make "See also" conform to the new syntax (#12756) (#12354)

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>
Co-authored-by: spageektti <git@spageektti.cc>
Co-authored-by: Lena <126529524+acuteenvy@users.noreply.github.com>

pages/common/nix-shell.md

@@ -1,7 +1,7 @@
 # nix-shell
 
 > Start an interactive shell based on a Nix expression.
-> See also: `tldr nix3 shell`.
+> See also: `nix3 shell`.
 > More information: <https://nixos.org/manual/nix/stable/command-ref/nix-shell.html>.
 
 - Start with nix expression in `shell.nix` or `default.nix` in the current directory: