Improve documentation example

[an3l]

• Documentation said that mysql client used in second container could
  use some-network. Problema with this (for the new users at least) is
  how to create the new network and that some-network excludes bridge
  network. Here is an example:

$ docker network create mariadb-net
$ docker network ls
NETWORK ID     NAME          DRIVER    SCOPE
6619c329efd7   bridge        bridge    local
c40fe8f5347a   host          host      local
ddff491eb0b3   mariadb-net   bridge    local
03bba7bb6438   none          null      local

$ docker run --network bridge --name mariadb-c1 -e MYSQL_ROOT_PASSWORD=root -d mariadb:10.5
9c64c725816e9950e92dfd2a0a65eb37e8c801e452ae2e5c3eb78c6907ef4d9d
$ docker run -it --network bridge --rm mariadb:10.5 mysql -hmariadb-c1 -uroot -proot
ERROR 2005 (HY000): Unknown MySQL server host 'mariadb-c1' (-2)

$ docker stop mariadb-c1 && docker rm mariadb-c1

$ docker run --network mariadb-net --name mariadb-c1 -e MYSQL_ROOT_PASSWORD=root -d mariadb:10.5

$ docker run -it --net mariadb-net --rm mariadb:10.5 mysql -hmariadb-c1 -uroot -proot
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 10.5.8-MariaDB-1:10.5.8+maria~focal mariadb.org binary distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]>

• Also in documentation when second/client container is created reference to
  some-network is not explained and this patch solves that.

[an3l]

Don't understand the problem with markdownfmt...

[tianon]

Thanks for the contribution!

I'm OK with adding --network some-network (in line with #1441), but if we do much more than that, I'm afraid we're sliding down the slope of duplicating the Docker basics documentation, which I think we need to assume basic familiarity with (the length of our documentation has a practical limit and we need to be careful that what we include is as straightforward as possible).

[an3l]

Hi,
thanks for the review.
So basically you think that much more is (+2 lines + in-line comment):
there shouldn't be a showcase how to create the network (2 lines) and adding the comment what network is (in-line comment), which is addressing the issue that people have when starting?
From my perspective docker documentation should explain everything regarding the functionality and addressing the problems which exist explicitly in the document that the user is currently using (in this case mariadb).
There are problems and should be explained (not to google about why doesn't work).
So I don't think there should be any trade-off (even if it is duplicating )regarding the functionality of the documentation.

[yosifkit]

Closing since this is included in #1889