docs: help pages for the time window, navigation, pause and trigger

src/help_window.cpp

@@ -34,6 +34,10 @@ constexpr HelpPage kPages[] = {
     {"Getting started", "Choosing a source", "/org/udpscope/help/02-source.txt"},
     {"Getting started", "Signals and calibration", "/org/udpscope/help/03-signals.txt"},
     {"Getting started", "Rows, layout and drag & drop", "/org/udpscope/help/04-layout.txt"},
+    {"Viewing", "Time window", "/org/udpscope/help/05-window.txt"},
+    {"Viewing", "Navigating the plot", "/org/udpscope/help/06-navigate.txt"},
+    {"Viewing", "Pause and play", "/org/udpscope/help/07-pause.txt"},
+    {"Viewing", "Trigger", "/org/udpscope/help/08-trigger.txt"},
 };
 constexpr int kPageCount = static_cast<int>(sizeof(kPages) / sizeof(kPages[0]));