Finished documentation about read-write splitting.
Update input-file-upload.md

fix docs
Merge pull request #4282 from dizews/patch-1

Update input-file-upload.md
Improved global configuration of assetmanager

Added `beforeCopy`, `afterCopy`, `forceCopy` properties to AssetManager

fixes #4209
elasticsearch 1.x breaking changes

all fine now

closes #2427
Fixes #4286: Update input-file-upload.md
Added Indonesian message translation
Merge pull request #4285 from yiisoft/global-asset-config

Improved global configuration of assetmanager
Fixes #4287: authorization link fix
test WIP
Added test.
all finished. [skip ci]
Merge pull request #4274 from yiisoft/feature-multiconnection

Support for separating Read/Write Database
Updated history [skip ci]
Update intro-upgrade-from-v1.md
Merge pull request #4289 from mrarthur/patch-2

Error in code example
Typos and errors in docs
Merge pull request #4291 from mrarthur/patch-3

Typos and errors in docs
Edited; already very clean!
concept-aliaese.md proofread.