kinfocenter, systemsettings: add page; spectacle: add example (#16302)

pages/common/spectacle.md

@@ -9,8 +9,12 @@
 
 - Capture a screenshot of the active window:
 
-`spectacle --activewindow`
+`spectacle {{[-a|--activewindow]}}`
 
 - Capture a screenshot of a specific region:
 
-`spectacle --region`
+`spectacle {{[-r|--region]}}`
+
+- Start another Spectacle instance so that you can screenshot Spectacle itself:
+
+`spectacle {{[-i|--new-instance]}}`

pages/linux/kinfocenter.md

@@ -0,0 +1,16 @@
+# kinfocenter
+
+> KDE information center to show system information.
+> More information: <https://manned.org/kinfocenter>.
+
+- Open the GUI:
+
+`kinfocenter`
+
+- List all possible KCM modules for `kinfocenter`:
+
+`kinfocenter --list`
+
+- Display help:
+
+`kinfocenter {{[-h|--help]}}`

pages/linux/systemsettings.md

@@ -0,0 +1,16 @@
+# systemsettings
+
+> KDE central settings program.
+> More information: <https://manned.org/systemsettings>.
+
+- Open the settings GUI:
+
+`systemsettings`
+
+- List all possible KCM modules for `systemsettings`:
+
+`systemsettings --list`
+
+- Display help:
+
+`systemsettings {{[-h|--help]}}`