README & gitignore updates

Author: mthierba

.gitignore

@@ -1 +1,2 @@
-*.pbix
+*.pbix
+*.pbit

README.md

@@ -13,6 +13,6 @@ A fully functioning and refreshable PBIT file can be generated from sources in t
 
 ## Generate PBIT file from sources
 
-    pbi-tools compile-pbix -folder ./pbix -format PBIT -outPath AdvWorksDW2020.pbit
+    pbi-tools compile -folder ./pbix -format PBIT -outPath AdvWorksDW2020.pbit
 
 _Requires `pbi-tools`, [1.0.0-beta.6](https://github.com/pbi-tools/pbi-tools/releases/tag/1.0.0-beta.6) or [later](https://github.com/pbi-tools/pbi-tools/releases/latest) release._