[Committers Guide] Fix paths in Steps for New Committers

* There is no authors.toml but authors.adoc

* Add `doc` in the path as in the other steps to make explicit that we refer
  to the `doc` repository.

* s/shared/share in `src` repository:

Approved by: 0mp (mentor)
Differential Revision: https://reviews.freebsd.org/D28590

documentation/content/en/articles/committers-guide/_index.adoc

@@ -2157,7 +2157,7 @@ Those who have been given commit rights to the FreeBSD repositories must follow
 
 . Add an Author Entity
 + 
-[.filename]#shared/authors.toml# - Add an author entity. Later steps depend on this entity, and missing this step will cause the [.filename]#doc/# build to fail. This is a relatively easy task, but remains a good first test of version control skills.
+[.filename]#doc/shared/authors.adoc# - Add an author entity. Later steps depend on this entity, and missing this step will cause the [.filename]#doc/# build to fail. This is a relatively easy task, but remains a good first test of version control skills.
 . Update the List of Developers and Contributors
 + 
 [.filename]#doc/en/articles/contributors/contrib-committers.adoc# - Add an entry to the "Developers" section of the link:{contributors}#staff-committers[Contributors List]. Entries are sorted by last name.
@@ -2180,7 +2180,7 @@ It is very important to have a current PGP/GnuPG key in the repository. The key
 ======
 . Update Mentor and Mentee Information
 + 
-[.filename]#base/head/shared/misc/committers-repository.dot# - Add an entry to the current committers section, where _repository_ is `doc`, `ports`, or `src`, depending on the commit privileges granted.
+[.filename]#base/head/share/misc/committers-repository.dot# - Add an entry to the current committers section, where _repository_ is `doc`, `ports`, or `src`, depending on the commit privileges granted.
 + 
 Add an entry for each additional mentor/mentee relationship in the bottom section.
 . Generate a Kerberos Password