Docs: Change "downloadable" to "offline" (#9782)

Replace 2 occurrences of "downloadable"

Author: benjaoming

docs/user/downloadable-documentation.rst

@@ -69,7 +69,7 @@ MkDocs and Docsify + more
    The common case for most documentation frameworks is that several alternative extensions exist supporting various output formats.
    Most of the extensions export the HTML outputs as another format (for instance PDF) through a conversion process.
 
-Because Sphinx supports the generation of downloadable formats through an official process,
+Because Sphinx supports the generation of offline formats through an official process,
 we are also able to support it officially.
 Other alternatives can also work,
 provided that you identify which extension you want to use and configure the environment for it to run.

docs/user/flyout-menu.rst

@@ -12,7 +12,7 @@ Functionality
 The flyout menu provides access to the following bits of Read the Docs functionality:
 
 * A :doc:`version switcher </versions>` that shows users all of the active, unhidden versions they have access to.
-* :doc:`Downloadable formats </downloadable-documentation>` for the current version, including HTML & PDF downloads that are enabled by the project.
+* :doc:`Offline formats </downloadable-documentation>` for the current version, including HTML & PDF downloads that are enabled by the project.
 * Links to the Read the Docs dashboard for the project.
 * Links to your :doc:`VCS provider </integrations>` that allow the user to quickly find the exact file that the documentation was rendered from.
 * A search bar that gives users access to our :doc:`/server-side-search/index` of the current version.