Document Docker Compose Version 2.3 (#3994)

And the new "target" parameter under "build"

Signed-off-by: Yong Wen Chua <me@yongwen.xyz>

_includes/content/compose-matrix.md

@@ -6,6 +6,7 @@ This table shows which Compose file versions support specific Docker releases.
 |      3.2                |       17.04.0+            |
 |      3.1                |       1.13.1+             |
 |      3.0                |       1.13.0+             |
+|      2.3                |       17.06.0+            |
 |      2.2                |       1.13.0+             |
 |      2.1                |       1.12.0+             |
 |      2.0                |       1.10.0+             |

compose/compose-file/compose-file-v2.md

@@ -178,6 +178,12 @@ build.
       context: .
       network: custom_network_1
 
+#### target
+
+> Added in [version 2.3](compose-versioning.md#version-23) file format
+
+Sets the name of the build-stage to build in a
+[multi-stage Dockerfile](/engine/userguide/eng-image/multistage-build.md).
 
 ### cap_add, cap_drop
 

compose/compose-file/compose-versioning.md

@@ -214,6 +214,16 @@ Introduces the following additional parameters:
 - [`init`](compose-file-v2.md#init)
 - [`scale`](compose-file-v2.md#scale)
 
+### Version 2.3
+
+An upgrade of [version 2.2](#version-22) that introduces new parameters only
+available with Docker Engine version **17.06+**.  Version 2.3 files are
+supported by **Compose 17.06+**.
+
+Introduces the following additional parameters:
+
+- [`target`](compose-file-v2.md#target)
+
 ### Version 3
 
 Designed to be cross-compatible between Compose and the Docker Engine's