Add a switchers chapter and fix drift found on a second manual pass

Add "Coming From Mac or Windows" as chapter 3: a translation layer for
Cmd/Win instincts rather than a feature tour.

Fill the remaining coverage gaps: fcitx5 input methods, laptop speaker
tuning, touchpad haptics, crash capture in the toggle table, the
installable font list, and the ChatGPT Desktop and Grok Bot entries.

Correct claims that drifted from the source: the network and bluetooth
bar icons no longer launch nmtui/bluetoothctl, monitor scaling steps
rather than cycles, and the display widget's scroll steps brightness.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

manual/27-filling-out-pdfs.md

@@ -0,0 +1,9 @@
+# Filling out PDFs
+
+Omarchy ships with a nice, basic PDF viewer called Document Viewer. This is the program that'll open any PDFs you just double click on.
+
+But you can only use Document Viewer to fill out PDFs that have been setup as forms. If you need to fill out PDFs that haven't, or you need to sign a PDF, you'll have to right-click the file, select _Open With..._, and pick Xournal++.
+
+Xournal++ will let you write anywhere on a PDF using the T tool. If you need to sign a document, you'll need an image of your signature, and you can use the Image tool to insert this signature and resize it.
+
+When you're done filling out the PDF, use _File > Export as PDF_ to save the final version.