fix spelling

Co-authored-by: Matt Fisher <mfisher87@gmail.com>

doc/source/user_guide/changelog/v1.3.0.rst

@@ -8,7 +8,7 @@ including other versions of icepyx.
     This is anticipated to be the last release in v1 of icepyx.
 
     NSIDC (the NASA DAAC that hosts ICESat-2 data) is transitioning their
-    API endpoint from the on-premesis EGI system to the cloud-based Harmony services.
+    API endpoint from the on-premises EGI system to the cloud-based Harmony services.
     icepyx is being updated to access these new services; the only change users
     will experience concerns services that are no longer available (e.g. reformatting).