FND-365 - Wording for precious metals currency identifiers needs work

Signed-off-by: Elisa Kendall ekendall@thematix.com

Description

Revised currency codes to correct definitions for precious metals in the code generation process and added language tags

Fixes: #1721 / FND-365

[x] I'm familiar with the FIBO developer quide. My contribution meets all the requirements described there.
[x] My contribution follows the principles of best practices for FIBO.
[x] My changes have been reconciled with latest master and no merge conflicts remain.
[x] This PR is related to exactly one issue. The issue is referenced by using a GitHub keyword such as "fixes", "closes", or "resolves".
[x] Hygiene tests have been applied by a PR with "(WIP)" in title.
[x] The issue has been tested locally using a reasoner (for ontology changes).