Subtask to #325: Document optimistic locking

[uweschaefer]

From @uweschaefer on 2019-03-26 11:23:36 +0000 UTC

Subtask to #325, should be branched from this branch

In markdown, see factcast-site/documentation/content/concept/caching* as a template

Copied from original issue: Mercateo/factcast#332

[uweschaefer]

From @uweschaefer on 2019-03-26 11:33:31 +0000 UTC

for reference: https://raw.githubusercontent.com/Mercateo/factcast/issue239_factstore_extensions/factcast-site/documentation/content/concept/caching.md

[uweschaefer]

From @uweschaefer on 2019-03-26 12:36:51 +0000 UTC

2 SP

[uweschaefer]

From @uweschaefer on 2019-04-08 10:56:11 +0000 UTC

open for review. #363

[uweschaefer]

From @uweschaefer on 2019-04-22 16:48:54 +0000 UTC

closed by #332