Corrected/changed variable names of the base64 and hex imports (instead of fmt) to correspond with the module name itself. (#375)

docs/stdlib-base64.md

@@ -1,7 +1,7 @@
 # Module - "base64"
 
 ```golang
-fmt := import("base64")
+base64 := import("base64")
 ```
 
 ## Functions

docs/stdlib-hex.md

@@ -1,7 +1,7 @@
 # Module - "hex"
 
 ```golang
-fmt := import("hex")
+hex := import("hex")
 ```
 
 ## Functions