Fix program descriptions (docstings).

* config/mailutils-config.c: Terminate docstring with a period.
* dotlock/dotlock.c: Likewise.
* frm/frm.c: Likewise.
* frm/from.c: Likewise.
* imap4d/imap4d.c: Likewise.
* maidag/maidag.c: Likewise.
* pop3d/pop3d.c: Likewise.
* readmsg/readmsg.c: Likewise.
* sieve/sieve.c: Likewise.

@@ -26,7 +26,7 @@
 #include "mailutils/libargp.h"
 
 const char *program_version = "mailutils-config (" PACKAGE_STRING ")";
-static char doc[] = N_("GNU mailutils-config -- display compiler and loader options needed for building a program with mailutils");
+static char doc[] = N_("GNU mailutils-config -- display compiler and loader options needed for building a program with mailutils.");
 static char args_doc[] = N_("[arg...]");
 
 static struct argp_option options[] = {

@@ -35,7 +35,7 @@
 
 const char *program_version = "GNU dotlock (" PACKAGE_STRING ")";
 static char doc[] =
-N_("GNU dotlock -- lock mail spool files")
+N_("GNU dotlock -- lock mail spool files.")
 "\v"
 N_("Returns 0 on success, 3 if locking the file fails because\
  it's already locked, and 1 if some other kind of error occurred.");

@@ -32,7 +32,7 @@ static int align = 0;      /* Tidy mode. -t option. */
 static int select_attribute;
 
 const char *program_version = "frm (" PACKAGE_STRING ")";
-static char doc[] = N_("GNU frm -- display From: lines");
+static char doc[] = N_("GNU frm -- display From: lines.");
 
 static struct attr_tab {
   char *name;      /* Attribute name */

@@ -23,7 +23,7 @@ char *sender_option;
 char *mailbox_name;
 
 const char *program_version = "from (" PACKAGE_STRING ")";
-static char doc[] = N_("GNU from -- display from and subject");
+static char doc[] = N_("GNU from -- display from and subject.");
 
 static struct argp_option options[] = {
   {"count",  'c', NULL,   0, N_("just print a count of messages and exit")},

@@ -55,7 +55,7 @@ char *ident_keyfile;
 int ident_encrypt_only;
 
 const char *program_version = "imap4d (" PACKAGE_STRING ")";
-static char doc[] = N_("GNU imap4d -- the IMAP4D daemon");
+static char doc[] = N_("GNU imap4d -- the IMAP4D daemon.");
 
 #define OPT_LOGIN_DISABLED  256
 #define OPT_TLS_REQUIRED    257

@@ -56,7 +56,7 @@ int reuse_lmtp_address = 1;
 
 const char *program_version = "maidag (" PACKAGE_STRING ")";
 static char doc[] =
-N_("GNU maidag -- the mail delivery agent")
+N_("GNU maidag -- the mail delivery agent.")
 "\v"
 N_("Debug flags are:\n\
   g - guimb stack traces\n\

@@ -54,7 +54,7 @@ int expire_on_exit = 0;       /* Delete expired messages on exit */
 static error_t pop3d_parse_opt  (int key, char *arg, struct argp_state *astate);
 
 const char *program_version = "pop3d (" PACKAGE_STRING ")";
-static char doc[] = N_("GNU pop3d -- the POP3 daemon");
+static char doc[] = N_("GNU pop3d -- the POP3 daemon.");
 
 #define OPT_LOGIN_DELAY     257
 #define OPT_STAT_FILE       258

@@ -34,7 +34,7 @@ static void print_body (mu_message_t);
 static int  string_starts_with (const char * s1, const char *s2);
 
 const char *program_version = "readmsg (" PACKAGE_STRING ")";
-static char doc[] = N_("GNU readmsg -- print messages");
+static char doc[] = N_("GNU readmsg -- print messages.");
 static error_t readmsg_parse_opt  (int key, char *arg, struct argp_state *astate);
 
 static struct argp_option options[] = 

@@ -51,7 +51,7 @@
 const char *program_version = "sieve (" PACKAGE_STRING ")";
 
 static char doc[] =
-N_("GNU sieve -- a mail filtering tool")
+N_("GNU sieve -- a mail filtering tool.")
 "\v"
 N_("Debug flags:\n\
   g - main parser traces\n\