docs: fix typos, punctuation in keywords_vs_identifiers.js (#1945)

Fix typos and punctuation, and improve some wordings a little.

examples/lexer/keywords_vs_identifiers/keywords_vs_identifiers.js

@@ -2,14 +2,14 @@
  * This example shows how to resolve the keywords vs identifiers ambiguity.
  * The order of TokenTypes in the lexer definition matters.
  *
- * If we place keywords before the Identifier than identifiers that have a keyword like prefix will not be
- * lexer correctly. For example, the keyword "for" and the identifier "formal".
+ * If we place keywords before the Identifier, then identifiers that have a keyword-like prefix will not be
+ * lexed correctly. For example, the keyword "for" and the identifier "formal".
  * The token vector will be ["for", "mal"] instead of ["formal"].
  *
- * On the other hand if we place keywords after the Identifier than they will never
- * be lexed as keywords as all keywords are usually valid identifiers.
+ * On the other hand, if we place keywords after the Identifier, then they will never
+ * be lexed as keywords, as all keywords are usually valid identifiers.
  *
- * The solution is to place the keywords BEFORE the Identifier with an added property
+ * The solution is to place the keywords BEFORE the Identifier with an additional property, longer_alt,
  * telling the lexer to prefer the longer identifier alternative if one is found.
  */
 
@@ -40,14 +40,14 @@ const Whitespace = createToken({
 })
 
 const keywordsVsIdentifiersLexer = new Lexer([
-  Whitespace, // Whitespace is very common in most languages so placing it first generally speeds up the lexing.
+  Whitespace, // Whitespace is very common in most languages so placing it first generally speeds up the lexing process.
 
-  While, // the actual keywords (While/For/Do) must appear BEFORE the Identifier Token as they are all a valid prefix of it's PATTERN.
-  For, // However the edge case of an Identifier with a prefix which is a valid keyword must still be handled, for example:
-  Do, // 'do' vs 'done' or 'for' vs 'forEach'. This is solved by defining 'Keyword.LONGER_ALT = Identifier'/
-  // thus each time a Keyword is detected the Lexer will also try to match a LONGER Identifier..
+  While, // the actual keywords (While/For/Do) must appear BEFORE the Identifier Token, as they are all a valid prefix of it's PATTERN.
+  For, // However, the edge case of an Identifier with a prefix, which is a valid keyword, must still be handled. For example:
+  Do, // 'do' vs 'done' or 'for' vs 'forEach'. This is solved by defining 'Keyword.LONGER_ALT = Identifier',
+  // thus each time a Keyword is detected, the Lexer will also try to match a LONGER Identifier.
 
-  Identifier // As mentioned above, the Identifier Token must appear after ALL the Keyword Tokens
+  Identifier // As mentioned above, the Identifier Token must appear after ALL the Keyword Tokens.
 ])
 
 module.exports = {