Grammar fixes for the Single Field Indexes page.

Signed-off-by: kay <kay.kim@10gen.com>
Standardize 'ObjectId' casing and omissions on the Single Field Indexes page.

Signed-off-by: kay <kay.kim@10gen.com>
Render a zip code as a string on the Single Field Indexes page.

In general, zip codes should be stored as strings in MongoDB because
numbers with leading zeroes are treated as octal numbers in JavaScript.

Signed-off-by: kay <kay.kim@10gen.com>