Rectify bup-split documentation for the fanout option.

The --fanout option is no longer the maximum number of objects in a
tree, but an average. The documentation, however was never updated and
this can lead to misunderstandings.

Also add a "bold" delimiter that was forgotten in the command summary in
its documentation page.

Signed-off-by: Gabriel Filion <lelutin@gmail.com>
Reviewed-by: Rob Browning <rlb@defaultvalue.org>

Documentation/bup-split.md

@@ -10,7 +10,7 @@ bup-split - save individual files to bup backup sets
 
 bup split [-r *host*:*path*] \<-b|-t|-c|-n *name*\> [-v] [-q]
   [\--bench] [\--max-pack-size=*bytes*] [-#]
-  [\--max-pack-objects=*n*] [\--fanout=*count]
+  [\--max-pack-objects=*n*] [\--fanout=*count*]
   [\--git-ids] [\--keep-boundaries] [filenames...]
 
 # DESCRIPTION
@@ -121,10 +121,8 @@ To get the data back, use `bup-join`(1).
     Usually there is no reason to change this.
 
 \--fanout=*numobjs*
-:   when splitting very large files, never put more than
-    this number of git blobs in a single git tree.  Instead,
-    generate a new tree and link to that.  Default is
-    4096 objects per tree.
+:   when splitting very large files, try and keep the number
+    of elements in trees to an average of *numobjs*.
 
 \--bwlimit=*bytes/sec*
 :   don't transmit more than *bytes/sec* bytes per second

cmd/split-cmd.py

@@ -8,7 +8,7 @@
 bup split <-t|-c|-b|-n name|--copy|--noop> [--bench] [filenames...]
 --
  Modes:
-b,blobs    output a series of blob ids
+b,blobs    output a series of blob ids.  Implies --fanout=0.
 t,tree     output a tree id
 c,commit   output a commit id
 n,name=    save the result under the given name
@@ -24,7 +24,7 @@
 bench      print benchmark timings to stderr
 max-pack-size=  maximum bytes in a single pack
 max-pack-objects=  maximum number of objects in a single pack
-fanout=    maximum number of blobs in a single tree
+fanout=    average number of blobs in a single tree
 bwlimit=   maximum bytes/sec to transmit to server
 #,compress=  set compression level to # (0-9, 9 is highest) [1]
 """