bitbake: bitbake-user-manual: revert change about PREFERRED_PROVIDERS

Partially reverting https://git.openembedded.org/bitbake/commit/?id=d1779e2f7789e516efae434b3781c981d0ef4ded

(Bitbake rev: 0556c7bdc82cf665faa141989f2e07dd59517735)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reported-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst

@@ -1230,9 +1230,9 @@ overview of their function and contents.
          PREFERRED_PROVIDER_virtual/libgl ?= "mesa"
 
    :term:`PREFERRED_PROVIDERS`
-      A colon-separated list to determine which recipe should be given
-      preference for cases where multiple recipes provide the same item.
-      Functionally, :term:`PREFERRED_PROVIDERS` is identical to
+      Determines which recipe should be given preference for cases where
+      multiple recipes provide the same item. Functionally,
+      :term:`PREFERRED_PROVIDERS` is identical to
       :term:`PREFERRED_PROVIDER`. However, the :term:`PREFERRED_PROVIDERS` variable
       lets you define preferences for multiple situations using the following
       form::