Fix broken links in tmy_to_power tutorial

- Replace broken rredc.nlr.gov TMY3 link with nsrdb.nlr.gov archive
- Use canonical https://docs.nlr.gov URL for PVUSA reference PDF
- Add trailing newline

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jason-curtis

docs/tutorials/tmy_to_power.ipynb

@@ -70,7 +70,7 @@
   {
    "cell_type": "markdown",
    "metadata": {},
-   "source": "pvlib comes with a couple of TMY files, and we'll use one of them for simplicity. You could also load a file from disk, or specify a url. See this NLR website for a list of TMY files:\n\nhttp://rredc.nlr.gov/solar/old_data/nsrdb/1991-2005/tmy3/by_state_and_city.html"
+   "source": "pvlib comes with a couple of TMY files, and we'll use one of them for simplicity. You could also load a file from disk, or specify a url. See this NLR website for a list of TMY files:\n\nhttps://nsrdb.nlr.gov/data-sets/archives"
   },
   {
    "cell_type": "code",
@@ -1511,7 +1511,7 @@
   {
    "cell_type": "markdown",
    "metadata": {},
-   "source": "Next, we will assume that the SAPM model is representative of the real world performance so that we can use scipy's optimization routine to derive simulated PVUSA coefficients. You will need to install scipy to run these functions.\n\nHere's one PVUSA reference:\n\nhttp://www.nlr.gov/docs/fy09osti/45376.pdf\n"
+   "source": "Next, we will assume that the SAPM model is representative of the real world performance so that we can use scipy's optimization routine to derive simulated PVUSA coefficients. You will need to install scipy to run these functions.\n\nHere's one PVUSA reference:\n\nhttps://docs.nlr.gov/docs/fy09osti/45376.pdf\n"
   },
   {
    "cell_type": "code",