Update cheatsheets

tldr/linux/google-chrome-stable

@@ -0,0 +1,13 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# google-chrome-stable
+
+> This command is an alias of `chromium`.
+> More information: <https://chrome.google.com>.
+
+- View documentation for the original command:
+
+`tldr chromium`

tldr/linux/opera-stable

@@ -0,0 +1,13 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# opera-stable
+
+> This command is an alias of `chromium`.
+> More information: <https://opera.com>.
+
+- View documentation for the original command:
+
+`tldr chromium`

tldr/linux/qm-guest-exec

@@ -20,6 +20,6 @@ source: https://github.com/tldr-pages/tldr.git
 
 `qm guest exec {{vm_id}} {{argument1 argument2...}} --timeout {{10}}`
 
-- Execute a specific command via a guest agent and forward input from STDIN until EOF to the guest agent:
+- Execute a specific command via a guest agent and forward input from `stdin` until EOF to the guest agent:
 
 `qm guest exec {{vm_id}} {{argument1 argument2 ...}} --pass-stdin 1`

tldr/linux/vivaldi-stable

@@ -0,0 +1,13 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# vivaldi-stable
+
+> This command is an alias of `chromium`.
+> More information: <https://vivaldi.com>.
+
+- View documentation for the original command:
+
+`tldr chromium`