bcache: doc: update Documentation/admin-guide/bcache.rst

bcache.rst is from the original bcache.txt which was merged in mainline
kernel v3.10. There are a few things changed in the past 7 years. This
patch updates bache.rst documents in following content,
- Update bcache-tools git repo to,
https://git.kernel.org/pub/scm/linux/kernel/git/colyli/bcache-tools.git/
- Update bcache kernel tree to mainline kernel tree,
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
- make-bcache util is replaced by the unified bcache util,
`make-bcache` now can be performed by `bcache make`

Signed-off-by: Coly Li <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Kent Overstreet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/admin-guide/bcache.rst

···
 Say you've got a big slow raid 6, and an ssd or three. Wouldn't it be
 nice if you could use them as cache... Hence bcache.
 
-Wiki and git repositories are at:
+The bcache wiki can be found at:
+  https://bcache.evilpiepirate.org
 
-  - https://bcache.evilpiepirate.org
-  - http://evilpiepirate.org/git/linux-bcache.git
-  - https://evilpiepirate.org/git/bcache-tools.git
+This is the git repository of bcache-tools:
+  https://git.kernel.org/pub/scm/linux/kernel/git/colyli/bcache-tools.git/
+
+The latest bcache kernel code can be found from mainline Linux kernel:
+  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
 
 It's designed around the performance characteristics of SSDs - it only allocates
 in erase block sized buckets, and it uses a hybrid btree/log to track cached
···
 to be flushed.
 
 Getting started:
-You'll need make-bcache from the bcache-tools repository. Both the cache device
+You'll need bcache util from the bcache-tools repository. Both the cache device
 and backing device must be formatted before use::
 
-  make-bcache -B /dev/sdb
-  make-bcache -C /dev/sdc
+  bcache make -B /dev/sdb
+  bcache make -C /dev/sdc
 
-make-bcache has the ability to format multiple devices at the same time - if
+`bcache make` has the ability to format multiple devices at the same time - if
 you format your backing devices and cache device at the same time, you won't
 have to manually attach::
 
-  make-bcache -B /dev/sda /dev/sdb -C /dev/sdc
+  bcache make -B /dev/sda /dev/sdb -C /dev/sdc
+
+If your bcache-tools is not updated to latest version and does not have the
+unified `bcache` utility, you may use the legacy `make-bcache` utility to format
+bcache device with same -B and -C parameters.
 
 bcache-tools now ships udev rules, and bcache devices are known to the kernel
 immediately.  Without udev, you can manually register devices like this::
···
 If bcache is not available in the kernel, a filesystem on the backing
 device is still available at an 8KiB offset. So either via a loopdev
 of the backing device created with --offset 8K, or any value defined by
---data-offset when you originally formatted bcache with `make-bcache`.
+--data-offset when you originally formatted bcache with `bcache make`.
 
 For example::
 
···
 
 After you boot back with bcache enabled, you recreate the cache and attach it::
 
-	host:~# make-bcache -C /dev/sdh2
+	host:~# bcache make -C /dev/sdh2
 	UUID:                   7be7e175-8f4c-4f99-94b2-9c904d227045
 	Set UUID:               5bc072a8-ab17-446d-9744-e247949913c1
 	version:                0
···
 
    The default metadata size in bcache is 8k.  If your backing device is
    RAID based, then be sure to align this by a multiple of your stride
-   width using `make-bcache --data-offset`. If you intend to expand your
+   width using `bcache make --data-offset`. If you intend to expand your
    disk array in the future, then multiply a series of primes by your
    raid stripe size to get the disk multiples that you would like.