prompt_* functions: shorten their descriptions

share/functions/prompt_hostname.fish

@@ -1,3 +1,3 @@
-function prompt_hostname --description 'Print the hostname, shortened for use in the prompt'
+function prompt_hostname --description 'short hostname for the prompt'
     string replace -r "\..*" "" $hostname
 end

share/functions/prompt_login.fish

@@ -1,4 +1,4 @@
-function prompt_login --description "Print a description of the user and host suitable for the prompt"
+function prompt_login --description "display user name for the prompt"
     if not set -q __fish_machine
         set -g __fish_machine
         set -l debian_chroot $debian_chroot

share/functions/prompt_pwd.fish

@@ -1,4 +1,4 @@
-function prompt_pwd --description 'Print the current working directory, shortened to fit the prompt'
+function prompt_pwd --description 'short CWD for the prompt'
     set -l options h/help d/dir-length= D/full-length-dirs=
     argparse -n prompt_pwd $options -- $argv
     or return