Some outdated links to fix

[jholdstock]

INFO    -  Doc file 'advanced/solo-proof-of-stake-voting.md' contains a link '../proof-of-stake/how-to-stake.md#pos-using-a-voting-service-provider-vsp', but the doc
           'proof-of-stake/how-to-stake.md' does not contain an anchor '#pos-using-a-voting-service-provider-vsp'.
INFO    -  Doc file 'faq/proof-of-stake/general.md' contains a link '../../proof-of-stake/how-to-stake.md#pos-using-a-voting-service-provider-vsp', but the doc 'proof-of-stake/how-to-stake.md'
           does not contain an anchor '#pos-using-a-voting-service-provider-vsp'.
INFO    -  Doc file 'research/schnorr-signatures.md' contains a link '#fnref:1', but there is no such anchor on this page. This seems to be a footnote that is never referenced.
INFO    -  Doc file 'wallets/spv.md' contains a link '../proof-of-stake/how-to-stake.md#pos-using-a-voting-service-provider-vsp', but the doc 'proof-of-stake/how-to-stake.md' does not contain
           an anchor '#pos-using-a-voting-service-provider-vsp'.
INFO    -  Doc file 'wallets/cli/dcrwallet-tickets.md' contains a link '../../proof-of-stake/how-to-stake.md#pos-using-a-voting-service-provider-vsp', but the doc
           'proof-of-stake/how-to-stake.md' does not contain an anchor '#pos-using-a-voting-service-provider-vsp'.
INFO    -  Doc file 'wallets/cli/startup-basics.md' contains a link '../../advanced/manual-cli-install.md#installation', but the doc 'advanced/manual-cli-install.md' does not contain an anchor
           '#installation'.
INFO    -  Doc file 'wallets/decrediton/decrediton-troubleshooting.md' contains a link '../../faq/wallets-and-seeds.md#9-i-have-lost-my-seed-what-can-i-do', but the doc
           'faq/wallets-and-seeds.md' does not contain an anchor '#9-i-have-lost-my-seed-what-can-i-do'.