Remove duplicate words inside documentation

I have removed repeated `the` inside the documentation

Signed-off-by: Akhil Raj <lf32.dev@gmail.com>
Link: https://lore.kernel.org/r/20220827145359.32599-1-lf32.dev@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: filesystems: caching/backend-api.rst: fix an object withdrawn API

There's no fscache_are_objects_withdrawn() helper at all to test if
cookie withdrawal is completed currently. The cache backend is using
fscache_wait_for_objects() to wait all objects to be withdrawn.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
Link: https://listman.redhat.com/archives/linux-cachefs/2022-April/006705.html # v1

docs: filesystems: caching/backend-api.rst: correct two relinquish APIs use

1. cache backend is using fscache_relinquish_cache() rather than
fscache_relinquish_cookie() to reset the cache cookie.

2. No fscache_cache_relinquish() helper currently, it should be
fscache_relinquish_cache().

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
Link: https://listman.redhat.com/archives/linux-cachefs/2022-April/006703.html # v1
Link: https://listman.redhat.com/archives/linux-cachefs/2022-April/006704.html # v2

fscache: Rewrite documentation

Rewrite the fscache documentation.

Changes
=======
ver #3:
- The volume coherency data is now an arbitrarily-sized blob, not a u64.

ver #2:
- Put quoting around some bits of C being referred to in the docs[1].
- Stripped the markup off the ref to the netfs lib doc[2].

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/20211130175119.63d0e7aa@canb.auug.org.au/ [1]
Link: https://lore.kernel.org/r/20211130162311.105fcfa5@canb.auug.org.au/ [2]
Link: https://lore.kernel.org/r/163819672252.215744.15454333549935901588.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906986754.143852.17703291789683936950.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967193834.1823006.15991526817786159772.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021585970.640689.3162537597817521032.stgit@warthog.procyon.org.uk/ # v4

docs: filesystems: caching/backend-api.txt: convert it to ReST

- Add a SPDX header;
- Adjust document and section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add table markups;
- Add it to filesystems/caching/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/5d0a61abaa87bfe913b9e2f321e74ef7af0f3dfc.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>