docs: Update DAX API function reference

[MazterQyou]

Check List

• Tests have been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made

This PR updates DAX API function reference, specifically:

• Document newly supported arithmetic functions along with their caveats: AVERAGEA, AVERAGEX, COUNTAX, COUNTBLANK, COUNTX, DISTINCTCOUNTNOBLANK, MAXA, MAXX, MINA, MINX, SUMX
• Document newly supported date and time functions along with their caveats: DAY, HOUR, MINUTE, MONTH, NOW, QUARTER, SECOND, TODAY, UTCNOW, UTCTODAY, WEEKDAY, YEAR
• Document newly supported information functions along with their caveats: ISAFTER, ISEVEN, ISODD, USERCULTURE
• Document newly supported logical functions along with their caveats: FALSE, IF, SWITCH, TRUE
• Document newly supported math and trig functions along with their caveats: ABS, ACOS, ASIN, ATAN, CEILING, COS, EXP, FLOOR, INT, LN, LOG, LOG10, MOD, MROUND, PI, POWER, QUOTIENT, RAND, ROUND, ROUNDDOWN, ROUNDUP, SIN, SQRT, SQRTPI, TAN, TRUNC
• Document newly supported text functions along with their caveats: CONCATENATE, EXACT, FIND, LEFT, LEN, LOWER, MID, REPT, RIGHT, SUBSTITUTE, TRIM, UPPER, VALUE