Improve naming of pages

Part of #1106 (closed) (read this issue for access to the full audit and recommendations).

Per 2.4.2 of the accessibility audit, page titles need to reflect the content of the page better. Currently, page titles are slightly confusing and not descriptive of the content within (e.g. the library page is listed as "Home - Funkwhale" and the about page as simply "Funkwhale"). Each page needs to be given an apt and descriptive title in order to make it more accessible.

• Change the title of the page https://open.audio/about from ‘Funkwhale’ to ‘About – Funkwhale’
• Change the title of the page https://open.audio/ from ‘Welcome – Funkwhale’ to ‘Home – Funkwhale’
• Change the title of the page https://open.audio/library ‘Home – Funkwhale’ to ‘Library – Funkwhale’

Audit section (section 2.4.2):

The page https://open.audio/about has a page title ‘Funkwhale’. This doesn’t describe the purpose of the page well enough. Consider using a page title consistent with the other page titles, such as ‘About – Funkwhale’.

The page https://open.audio/ is titled ‘Welcome – Funkwhale’, whereas the page https://open.audio/library is titled ‘Home – Funkwhale’. This creates some confusion as it seems that https://open.audio/ is the Homepage. Consider using page titles that describe the purpose of the page clearer, such as ‘Home – Funkwhale’ for the open.audio and ‘Library – Funkwhale’ for the library page.