[Component][Finder] path(), notPath() methods
added some doc about optional sections

refs symfony/symfony#5688
[component][console] Initial documentation to support symfony/symfony#3501
[#1765] Making a few tweaks to the console progress update thanks to @lyrixx, @stof and @WouterJ
Merge branch '2.1'
Merge branch '2.1'
This is the second-half of a fix for a bad merge (merged master into 2.1).

This was fixed by reverting that merge on 2.1, merging 2.1 into master (as normal),
then reverting the revert to restore the changes on master.

Revert "This reverts an improper merge - master was merged into 2.1 by mistake."

This reverts commit 3300ab3586b76cef9a65558f942abd7a1e856165.
Merge branch '2.1'
Merge pull request #1788 from schmittjoh/patch-1

added some doc about optional sections
[#1788] Adding some :method: syntax, versionadded and other small tweaks to new optional Config additions
[Security] added new documentation about the PBKDF2 password encoder
Merge branch '2.1'

* 2.1:
  fixed some markup issues
  Tweaks per @WouterJ
  Fixed typo in documentation/overview
  Fixing typo thanks to @richardmiller
  [#1758] Minor tweaks - including fixing syntax errors around the image directive and describing the image
  added a new chapter about the Symfony release process
  Remove extra word
  Add missing words
  Try to fix a link
  Add missing apostrophe
  added missing letter
  fix minor typo
Merge branch '2.1'
Merge pull request #1779 from sstok/security_encoder_pbkdf2_doc

[Security] added new documentation about PBKDF2 password encoder for 2.2
Merge remote-tracking branch 'origin/master'
[#1779] Tweaks to PBKDF2 reference docs - mostly wording and moving it a bit lower
Update reference/configuration/framework.rst

This PR is related to this one https://github.com/symfony/symfony/pull/5347.
Update reference/dic_tags.rst

Adding tags to the tag list reference
Update reference/configuration/framework.rst

Changing backticks
added the CMF in the main Symfony docs