Corrected a typo and improved readability (#29300)
Corrected a typo and improved readability (#29300)

1. Corrected typo from "sequencial" to "sequential"
2. Corrected the grammar for the sentence "primitive and reference both form of datatypes are allowed" for better readability
3. Added on to the following sentence to make it less redundant; otherwise it would have been just a repeat of the sentence before it.
4. Changed "indexes" to "elements" because an index is just a list of numbers, so saying that "an array can be instantiated to a set number of indexes" would be confusing.
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