[OYPD-519] Add alt text to the open category buttons on the sub category page.

[ivan-berezhnov]

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Jira issue:

https://propeople-us.atlassian.net/browse/OYPD-519
Drupal.org issue: https://www.drupal.org/node/2889604

Steps to review:

• go to frontpage
• in the main menu click on "Program" and click on any category
• in the list of subcategory find button with text "Open category"
• check link have title attribute with node name as text in H2

[gundevel]

Build comment file:

===============

Environment	Link
Fresh OpenY installation	http://ci.openymca.org/build1744
Upgraded(upgrade path) installation	http://upgrade.openy-dev.ffwua.com/build1744
Installation process	http://install.openy-dev.ffwua.com/build1744/install.php

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[gundevel]

Decoupling report http://ci.openymca.org/build1744

[gundevel]

Accessibility report http://ci.openymca.org/build1744