help: Delete about-diff-public-private.page

Deleted page. The essence of the page is in the description to the PGP
section.
help: Delete about-pgp.page

Deleted about-pgp.page
The important bits from the page can be found in the pgp landing page.
help: Delete about-ssh.page

Deleted page.
Included important information from the page in the ssh.page(Landing
page for SSH keys.)
Move key-fingerprint page to the misc section.
help: Remove learn-about-keys section.

Remove the guide page.
Important bits from pages that were listed here, are going to be scattered as
notes in different pages so that help users can find the information
they need on the same page, and also to reduce the content in the help.
help: Remove MISC section from the index
help: Makes changes to misc-key-fingerprint.page

Change index.
Link page to PGP and SSH landing pages.
Help: Make changes to misc-key-backup.page

Link page to SSH and PGP sections.
Rename subkeys.page ->pgp-subkeys.page
help: Fixup links in all pages.

Resolved all string conflicts arising because of renaming pages and
moving them.
help: Reword keyring-change-default.page
help: Minor edits to keyring-lock.page
help: Minor edits to keyring-unlock.page
help: Minor edits to keyring-update-password.page
help: Minor edits to password-view.page
help: Minor edits to pgp-create.page
help: Minor edits to pgp-expiration-change.page
help: Minor edits to pgp-photoid.page
help: Minor edits to pgp-publish.page
help: Minor edits to pgp-retrieve-remote.page