More info on resource constraints in Compose v3 and v2 (#4651)

* added more info about resource constraints to Compose docs

Signed-off-by: Victoria Bialas <victoria.bialas@docker.com>

* fixed link in Compose docs, added instructions in test for adding custom target link link IDs

Signed-off-by: Victoria Bialas <victoria.bialas@docker.com>

* fixed links

Signed-off-by: Victoria Bialas <victoria.bialas@docker.com>

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

@@ -1088,6 +1088,8 @@ then read-write will be used.
       - restart: always
       - restart: on-failure
 
+{: id="cpu-and-other-resources"}
+
 ### cpu_count, cpu_percent, cpu\_shares, cpu\_quota, cpus, cpuset, domainname, hostname, ipc, mac\_address, mem\_limit, memswap\_limit, mem\_swappiness, mem\_reservation, oom_score_adj, privileged, read\_only, shm\_size, stdin\_open, tty, user, working\_dir
 
 Each of these is a single value, analogous to its

compose/compose-file/index.md

@@ -46,7 +46,7 @@ services:
         delay: 10s
       restart_policy:
         condition: on-failure
-        
+
   db:
     image: postgres:9.4
     volumes:
@@ -650,8 +650,12 @@ Configures resource constraints. This replaces the older resource constraint
 options in Compose files prior to version 3 (`cpu_shares`, `cpu_quota`,
 `cpuset`, `mem_limit`, `memswap_limit`, `mem_swappiness`).
 
-Each of these is a single value, analogous to its
-[docker service create](/engine/reference/commandline/service_create.md) counterpart.
+Each of these is a single value, analogous to its [docker service
+create](/engine/reference/commandline/service_create.md) counterpart.
+
+In this general example, the `redis` service is constrained to use no more than
+50M of memory and `0.001` (0.1%) of available processing time (CPU), and has
+`20M` of memory and `0.0001` CPU time reserved (as always available to it).
 
 ```none
 version: '3'
@@ -668,6 +672,20 @@ services:
           memory: 20M
 ```
 
+The topics below describe available options to set resource constraints on
+services or containers in a swarm.
+
+> Looking for options to set resources on non swarm mode containers?
+>
+> The options described here are specific to the
+`deploy` key and swarm mode. If you want to set resource constraints
+on non swarm deployments, use
+[Compose file format version 2 CPU, memory, and other resource
+options](compose-file-v2.md#cpu-and-other-resources).
+If you have further questions, please refer to the discussion on the GitHub
+issue [docker/compose/4513](https://github.com/docker/compose/issues/4513){: target="_blank" class="_"}.
+{: .important}
+
 ##### Out Of Memory Exceptions (OOME)
 
 If your services or containers attempt to use more memory than the system has

test.md

@@ -75,6 +75,8 @@ https://github.com/docker/docker.github.io/tree/master/docker-cloud/images
 - [a markdown link that opens in a new window](https://docker.com/){: target="_blank" class="_" }
   (the `class="_"` trick prevents Atom from italicizing the whole rest of the file until it encounters another underscore.)
 
+- [a markdown link to a custom target ID](#custom-target-id)
+
 - <a href="https://docker.com/">an HTML link</a>
 
 - <a href="https://docker.com/" target="_blank" class="_">an HTML link that opens in a new window</a>
@@ -85,6 +87,18 @@ https://github.com/docker/docker.github.io/tree/master/docker-cloud/images
 
 (you can also specify `org=foo` to use a Github organization other than Docker).
 
+{: id="custom-target-id"}
+
+#### Using a custom target ID
+This topic has a custom target ID above its heading that can be used to link to
+it, in addtion to, or instead of, the default concatenated heading style.
+
+You can use custom targets to link to headings or even paragraphs.
+
+An example of a custom target ID in the documentation is the topic on
+[Compose file version 2 topic on CPU and other resources](/compose/compose-file/compose-file-v2.md#cpu-and-other-resources).
+It has a long heading that breaks the normal markdown linking mechanism,
+so we added a custom ID above the target heading.
 
 ### Images