borg create help: document format tags, fixes #894

docs: rephrased, more useful examples

borg/archiver.py

@@ -997,6 +997,9 @@ class Archiver:
         '.checkpoint.N' (with N being a number), because these names are used for
         checkpoints and treated in special ways.
 
+        In the archive name, you may use the following format tags:
+        {now}, {utcnow}, {fqdn}, {hostname}, {user}, {pid}
+
         To speed up pulling backups over sshfs and similar network file systems which do
         not provide correct inode information the --ignore-inode flag can be used. This
         potentially decreases reliability of change detection, while avoiding always reading

docs/usage.rst

@@ -301,10 +301,9 @@ Examples
     # Even slower, even higher compression (N = 0..9)
     $ borg create --compression lzma,N /path/to/repo::arch ~
 
-    # Format tags available for archive name:
-    # {now}, {utcnow}, {fqdn}, {hostname}, {user}, {pid}
-    # add short hostname, backup username and current unixtime (seconds from epoch)
-    $ borg create  /path/to/repo::{hostname}-{user}-{now:%s} ~
+    # Use short hostname, user name and current time in archive name
+    $ borg create /path/to/repo::{hostname}-{user}-{now} ~
+    $ borg create /path/to/repo::{hostname}-{user}-{now:%Y-%m-%d_%H:%M:%S} ~
 
 .. include:: usage/extract.rst.inc