Minor index tweaks

Author: marijnh

01_values.md

@@ -20,7 +20,7 @@ In the computer's world, there is only data. You can read data, modify data, cre
 
 _Bits_ are any kind of two-valued things, usually described as zeros and ones. Inside the computer, they take forms such as a high or low electrical charge, a strong or weak signal, or a shiny or dull spot on the surface of a CD. Any piece of discrete information can be reduced to a sequence of zeros and ones and thus represented in bits.
 
-{{index "binary number", radix, "decimal number"}}
+{{index "binary number", "decimal number"}}
 
 For example, we can express the number 13 in bits. This works the same way as a decimal number, but instead of 10 different ((digit))s, we have only 2, and the weight of each increases by a factor of 2 from right to left. Here are the bits that make up the number 13, with the weights of the digits shown below them:
 

04_data.md

@@ -1013,8 +1013,6 @@ Building up an array is most easily done by first initializing a binding to `[]`
 
 Since the end boundary is inclusive, you'll need to use the `<=` operator rather than `<` to check for the end of your loop.
 
-{{index "arguments object"}}
-
 The step parameter can be an optional parameter that defaults (using the `=` operator) to 1.
 
 {{index "range function", "for loop"}}

21_skillsharing.md

@@ -40,7 +40,7 @@ A common solution to this problem is called _((long polling))_, which happens to
 
 ## Long polling
 
-{{index firewall, notification, "long polling", network, [browser, security]}}
+{{index notification, "long polling", network, [browser, security]}}
 
 To be able to immediately notify a client that something changed, we need a ((connection)) to that client. Since web browsers do not traditionally accept connections and clients are often behind ((router))s that would block such connections anyway, having the server initiate this connection is not practical.