release: 3.0.1

Bump the workspace to 3.0.1 and bring the user guide up to date: an RDP
chapter, shell integration and inline images, SSH certificates and CAs,
known_hosts import/export, stored credentials and master password change,
profile sync (replacing the Alchementary Link migration chapter), the
Diagnostics tab and log, and refreshed screenshots throughout. The welcome
screen's protocol line now lists RDP.

docs/guide/tools/screenshots.sh

@@ -90,9 +90,10 @@ shot editor-serial    --open editor:serial
 shot editor-telnet    --open editor:telnet
 shot editor-raw       --open editor:raw
 shot editor-vnc       --open editor:vnc
+shot editor-rdp       --open editor:rdp
 shot editor-irc       --open editor:irc
 shot editor-github    --open editor:github
-for t in general terminal security knownhosts help about; do shot "settings-$t" --open "settings:$t"; done
+for t in general terminal security knownhosts diagnostics help about; do shot "settings-$t" --open "settings:$t"; done
 shot keys             --open keys
 shot snippets         --open snippets
 shot triggers         --open triggers