Fixed formatting

A missing space caused a </code> tag to not close correctly.
Documented that "empty_value" can be used for expanded choice fields
[#2605] Minor tweak to language
Added new tag
[#2630] Tweaking language
Merge pull request #2685 from florianeckerstorfer/patch-1

Fixed formatting
Adding lazy services documentation as of symfony/symfony#7890
(cherry picked from commit 50905ff253e5e1164b377ad5f285d1c439e7bdb7)
Applying changes suggested by @WouterJ, adding lazy_services to components map
(cherry picked from commit 931091d8e3aa0b9d4f1393d313388d5ee1a5d47d)
[#2619] Tweaks for new proxy/lazy services entry
(cherry picked from commit d7ea3a540a5dc425bf1d16f4113746975404da38)
Merge branch '2.3'