Fix a typo in shims/README.md

Signed-off-by: Gary Shen <[email protected]>

shims/README.md

@@ -26,7 +26,7 @@ In the following we provide recipes for typical scenarios addressed by the Shim
 It's among the easiest issues to resolve. We define a method in SparkShims
 trait covering a superset of parameters from all versions and call it 
 ```
-ShimLoader.gerSparkShims.methodWithDiscrepancies(p_1, ..., p_n)
+ShimLoader.getSparkShims.methodWithDiscrepancies(p_1, ..., p_n)
 ```
 instead of referencing it directly. Shim implementations are in charge of dispatching it further 
 to correct version-dependent methods. Moreover, unlike in the below sections