doc: fix typo (superfluous "no")

Signed-off-by: Adam Spiers <aspiers@suse.com>
doc: fix incorrect equalities

The previous punctuation accidentally implied that K == 1 and M == -1.

Signed-off-by: Adam Spiers <aspiers@suse.com>
doc: fix typos in diagram for incomplete write

In this example of a write of v2 of the object being interrupted, OSD2
would never have any version of the D1 chunk.  It only has the old v1
version of the D2 chunk.

Signed-off-by: Adam Spiers <aspiers@suse.com>
Merge pull request #2939 from aspiers/fix/architecture-docs

minor tweaks to architecture document

Reviewed-by: Sage Weil <sage@redhat.com>