fix pandas lmm notebook link (#430)

Signed-off-by: William Brandler <William.Brandler@databricks.com>

Author: williambrandler

docs/source/_static/notebooks/tertiary/pandas-lmm.html

@@ -18,7 +18,7 @@
 # COMMAND ----------
 
 # DBTITLE 1,Get the population annotation for samples in 1000genomes phase 3
-pop = pd.read_csv('ftp://ftp.1000genomes.ebi.ac.uk/vol1/ftp/release/20130502/integrated_call_samples_v3.20200731.ALL.ped', sep='\t')
+pop = pd.read_csv('https://ftp.1000genomes.ebi.ac.uk/vol1/ftp/release/20130502/integrated_call_samples_v3.20200731.ALL.ped', sep='\t')
 pop.head(5)
 
 # COMMAND ----------