tmpfs: fix Documentation nits

Fix a typo, punctuation, use uppercase for CPUs, and limit
tmpfs to keeping only its files in virtual memory (phrasing).

Link: https://lkml.kernel.org/r/20201202010934.18566-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/filesystems/tmpfs.rst

@@ -4,7 +4,7 @@
 Tmpfs
 =====
 
-Tmpfs is a file system which keeps all files in virtual memory.
+Tmpfs is a file system which keeps all of its files in virtual memory.
 
 
 Everything in tmpfs is temporary in the sense that no files will be
@@ -35,7 +35,7 @@ tmpfs has the following uses:
    memory.
 
    This mount does not depend on CONFIG_TMPFS. If CONFIG_TMPFS is not
-   set, the user visible part of tmpfs is not build. But the internal
+   set, the user visible part of tmpfs is not built. But the internal
    mechanisms are always present.
 
 2) glibc 2.2 and above expects tmpfs to be mounted at /dev/shm for
@@ -50,7 +50,7 @@ tmpfs has the following uses:
    This mount is _not_ needed for SYSV shared memory. The internal
    mount is used for that. (In the 2.3 kernel versions it was
    necessary to mount the predecessor of tmpfs (shm fs) to use SYSV
-   shared memory)
+   shared memory.)
 
 3) Some people (including me) find it very convenient to mount it
    e.g. on /tmp and /var/tmp and have a big swap partition. And now
@@ -83,7 +83,7 @@ If nr_blocks=0 (or size=0), blocks will not be limited in that instance;
 if nr_inodes=0, inodes will not be limited.  It is generally unwise to
 mount with such options, since it allows any user with write access to
 use up all the memory on the machine; but enhances the scalability of
-that instance in a system with many cpus making intensive use of it.
+that instance in a system with many CPUs making intensive use of it.
 
 
 tmpfs has a mount option to set the NUMA memory allocation policy for