docs: complete aggregation function list and fix typo in aggregate.md

[prql-bot]

Problem

Two accuracy issues in aggregate.md, found during the nightly code-quality survey:

1. Incomplete aggregation function list. The note claims "all declared aggregation functions are min, max, count, count_distinct, average, stddev and sum", but the ## Aggregate functions section of std.prql also declares all, any and concat_array. (PR docs: correct aggregation function list in aggregate.md #6002 previously corrected avg→count_distinct but didn't audit the rest of the section.)
2. Garbled sentence. "PRQL will interpret such attempts functions as window functions" contained a stray word.

Solution

• Add all, any and concat_array so the list matches the functions actually declared under ## Aggregate functions in std.prql.
• Remove the stray "functions" so the sentence reads "PRQL will interpret such attempts as window functions".

Testing

Documentation-only prose change (the runnable PRQL blocks are untouched), so no test is added. Verified the list against the let declarations in std.prql and confirmed the note block keeps its manual <!-- prettier-ignore --> wrapping.