Improve description of Julia keywords

doc/src/base/base.md

@@ -37,6 +37,21 @@ ans
 
 ## Keywords
 
+This is the list of reserved keywords in Julia:
+`baremodule', `begin', `break', `catch', `const', `continue', `do',
+`else', `elseif', `end', `export', `false', `finally', `for', `function',
+`global', `if', `import', `let', `local', `macro', `module', `quote',
+`return', `struct', `true', `try', `using', `while'.
+Those keywords are not allowed to be used as variable names.
+
+The follwoing two word sequences are reserved:
+`abstract type`, `mutable struct`, `primitive type`.
+However, you can create variables with names:
+`abstract`, `mutable`, `primitive` and `type`.
+
+Finally `where` is resolved contextually as a keyword in parametric method
+definition syntax, but creation of variable named `where` is allowed.
+
 ```@docs
 module
 export
@@ -65,6 +80,9 @@ struct
 mutable struct
 abstract type
 primitive type
+where
+true
+false
 ...
 ;
 ```