Add some mediocre manpages

I'm not particularly happy to write in mdoc but here goes.

CMakeLists.txt

@@ -26,6 +26,7 @@ target_compile_definitions (${PROJECT_NAME} PUBLIC
 include (GNUInstallDirs)
 install (TARGETS ${PROJECT_NAME} DESTINATION ${CMAKE_INSTALL_BINDIR})
 install (PROGRAMS ${PROJECT_NAME}-install DESTINATION ${CMAKE_INSTALL_BINDIR})
+install (FILES sdn.1 sdn-install.1 DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
 install (FILES LICENSE DESTINATION ${CMAKE_INSTALL_DOCDIR})
 
 set (CPACK_PACKAGE_DESCRIPTION_SUMMARY "Directory navigator")

sdn-install.1

@@ -0,0 +1,30 @@
+.Dd October 26, 2020
+.Dt SDN-INSTALL 1
+.Os Linux
+.Sh NAME
+.Nm sdn-install
+.Nd integrate sdn with the shell
+.Sh SYNOPSIS
+.Nm sdn-install
+.Op Fl s Ar shell
+.Op Fl p Ar - | rcpath
+.Sh DESCRIPTION
+.Nm
+integrates
+.Xr sdn 1
+with your shell, binding it to M-o.  If the navigator has already been
+integrated, it updates the snippet in-place.
+.Pp
+The options are as follows:
+.Bl -tag -width Ds
+.It Fl p Ar -
+Merely print the integration snippet for the appropriate shell to the standard
+output, not changing anything.
+.It Fl p Ar rcpath
+Install the integration snippet into a different shell initialization file than
+your user's default one.
+.It Fl s Ar shell
+If you want to integrate
+.Xr sdn 1
+with a different shell than you're running, use this option to specify it.
+.El

sdn.1

@@ -0,0 +1,38 @@
+.Dd October 26, 2020
+.Dt SDN 1
+.Os Linux
+.Sh NAME
+.Nm sdn
+.Nd simple directory navigator
+.Sh SYNOPSIS
+.Nm sdn
+.Op Ar line Ar point
+.Sh DESCRIPTION
+.Nm
+is a simple directory navigator that you can invoke while editing shell
+commands.  Use the
+.Xr sdn-install 1
+script to integrate it with your shell, then invoke it with M-o.
+.Sh ENVIRONMENT
+.Bl -tag -width 15n
+.It Ev LS_COLORS
+Used to retrieve filename colours.  The format is described in
+.Xr dir_colors 5
+and you can use the
+.Xr dircolors 1
+utility to initialize this variable.
+.It Ev PAGER
+The viewer program to be launched by the F3 key binding as well as to show
+the internal help message.
+.It Ev VISUAL , Ev EDITOR
+The editor program to be launched by the F4 key binding.
+.El
+.Sh FILES
+.Bl -tag -width 25n -compact
+.It Pa ~/.config/sdn/config
+Program configuration and state.
+.It Pa ~/.config/sdn/bindings
+Key binding overrides.
+.It Pa ~/.config/sdn/look
+Redefine terminal attributes for UI elements.
+.El