Fixed version for composer install
add link to form testing chapter in test section
Moved 'contributing' images to their own directory
fix name of the Yaml component

The component name that is used in the code as well as in the issue
tracker used by the symfony/symfony repository is Yaml (instead of
YAML). Therefore, this should also be the name being used in the
documentation.
replace "Symfony2" with "Symfony"
Added a note about the lacking features of Yaml Component
Fix method for adding placholders in progressBar

The method is called setPlaceholderFormatterDefinition and not setPlaceholderFormatter
The name of the placeholder must not be encapsulated in %
Missing backtick, thanks to @Baptouuuu
Reverts c723d8dd546412b08ffaf3846b5574f4f4021418
Missing backtick, thanks to @Baptouuuu
Fixed code highlighting
minor #4190 add link to form testing chapter in test section (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

add link to form testing chapter in test section

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

The confusion in symfony/symfony#11774 made me think that we could improve the links between the testing and the form section when it comes to testing forms.

Commits
-------

a2dbd36 add link to form testing chapter in test section
minor #4199 fix name of the Yaml component (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

fix name of the Yaml component

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | related to #4189

The component name that is used in the code as well as in the issue tracker used by the symfony/symfony repository is Yaml (instead of YAML). Therefore, this should also be the name being used in the documentation.

Commits
-------

5187768 fix name of the Yaml component
minor #4200 Moved 'contributing' images to their own directory (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
----------

Moved 'contributing' images to their own directory

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | #3192

The PDF version of the "Contributing Guide" doesn't show the images (as reported in #3192). The rest of the PDFs correctly show them. Although I don't know the exact cause of the error, the "Contributing" guide images weren't stored in their own subdirectory inside `images/` and named after the book. That's the only difference between the right and the wrong PDF files.

For compatibility reasons I've left on purpose the original images at their location and just made a copy in the new directory.

Commits
-------

fc15b65 Moved 'contributing' images to their own directory
minor #4208 Added a note about the lacking features of Yaml Component (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
----------

Added a note about the lacking features of Yaml Component

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | 2.3+
| Fixed tickets | -

In `symfony/symfony` repository there are a lot of issues reporting errors of the Yaml Component. These aren't errors but lacking features of the Yaml Component.

This PR tries to clearly state that Yaml Component lacks lots of features on purpose and provides a simple list of the most notable missing features.

Commits
-------

fe45194 Added a note about the lacking features of Yaml Component
minor #4205 replace "Symfony2" with "Symfony" (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

replace "Symfony2" with "Symfony"

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | #4203

Commits
-------

3ba3d27 replace "Symfony2" with "Symfony"
bug #4209 Fix method for adding placholders in progressBar (danez)

This PR was merged into the 2.5 branch.

Discussion
----------

Fix method for adding placholders in progressBar

The method is called setPlaceholderFormatterDefinition and not setPlaceholderFormatter

see [here][1]

Edit:
I found another glitch: The name of the placeholder must not be packed in %-characters, like it is the case when using the placeholders in the format. As you can see [here][2] the defaults are also not like this and best indication:  it does not work if doing like in the docs :)

[1]: https://github.com/symfony/symfony/blob/2.5/src/Symfony/Component/Console/Helper/ProgressBar.php#L82

[2]: https://github.com/symfony/symfony/blob/2.5/src/Symfony/Component/Console/Helper/ProgressBar.php#L486

Commits
-------

f3ef9dc The name of the placeholder must not be encapsulated in %
fb0e79c Fix method for adding placholders in progressBar
minor #4212 Missing backtick, thanks to @Baptouuuu (WouterJ)

This PR was merged into the 2.5 branch.

Discussion
----------

Missing backtick, thanks to @Baptouuuu

See https://github.com/symfony/symfony-docs/pull/4134

Commits
-------

dadaea3 Missing backtick, thanks to @Baptouuuu
minor #4215 Fixed code highlighting (WouterJ)

This PR was merged into the 2.3 branch.

Discussion
----------

Fixed code highlighting

| Q   | A
| --- | ---
| Doc fix? | yes
| New docs? | no
| Applies to | all
| Fixed tickets | -

 > Double quoted strings are the only scalar style capable of expressing arbitrary strings, by using “\” escape sequences.
 > - http://yaml.org/spec/1.1/#id904245

`\w` and `\d` are invalid escape sequences in Yaml, causing the Yaml highlighter to fail.

Commits
-------

f4b5dc6 Fixed code highlighting