[fix] correct date-time and encrypt-digest function doc issues

[boluor]

Summary

Fixes 19 small documentation issues across the date-time and encrypt-digest function references. Each item below is independent.

date-time-functions

• quarters-add.md — error messages in two out of range examples named month_add (a copy-paste from months-add.md); corrected to quarters_add.
• sec-to-time.md — the description gave the seconds bound of TIME as ±3023999; the real max for 838:59:59 is 3020399 (838*3600 + 59*60 + 59). Both occurrences corrected.
• second-ceil.md / second-floor.md — Return Value paragraph used \<date_or_time_expr>`while the parameters table uses``; unified on ``. The same files also had a leftover Chinese link label [timestamptz的转换]inside the English doc; replaced with[timestamptz conversion]`.
• sub-time.md / add-time.md — two of the three relative links in the parameter row had an extra ../ and a stray literal docs/ segment (../../../../../docs/sql-manual/...); aligned to the sibling link's correct form ../../../../sql-manual/....
• time-format.md — a stray closing ``` fence sat at the very end of the file (after the Note) with no matching opener; removed.
• timestampadd.md — the second -- Unit not supported, invalid example actually triggers an out-of-range error, not an unsupported-unit error; the comment is updated to match the actual error.
• timestampdiff.md — the Description said "behaves consistently with the [date_diff function] in MySQL"; the matching MySQL function is TIMESTAMPDIFF. Function name and URL anchor corrected.
• to-days.md / unix-timestamp.md / utc-time.md — misaligned ASCII result-table borders. utc-time.md additionally had a top border missing its leading +.
• week-floor.md — an error label read RROR 1105 (HY000): (missing the leading E); corrected to ERROR 1105 (HY000):.
• week.md — the mode-description table was enclosed in a ```sql fence and rendered as raw code; the fence is removed so the markdown table renders normally (consistent with yearweek.md).
• week.md / weekday.md / weekofyear.md — the parameters table key was \<datetime_or_date>`while the Syntax used`<date_or_time_expr>`; unified on `<date_or_time_expr>``.
• weekofyear.md — a sentence said "the 1st week of the current year starts from the next Sunday". The function uses Monday-start weeks (mode-3 default), so corrected to "next Monday".
• year-ceil.md / year-floor.md — <period> description said "how many seconds each period consists of" / "Default is 1 second" (copy-paste from the second-ceil docs); corrected to "years" / "1 year".
• weeks-sub.md — error messages echoed weeks_add instead of weeks_sub; corrected.
• years-sub.md — error messages echoed year_add instead of years_sub; corrected.
• weeks-diff.md / years-diff.md — the null_input1 / null_input2 result tables had rulers one character narrower than the data cells; widened.
• year-ceil.md / year-floor.md — the TimeStampTz result tables had header rows one character shorter than their rulers; padded.

encrypt-digest-functions

• aes-encrypt.md — the key-padding paragraph said "if the key input by the user is less than 16 bits"; the unit used elsewhere in the same paragraph is bytes (128/8 = 16 bytes). Corrected to "bytes".
• aes-decrypt.md / aes-encrypt.md — frontmatter description referenced AESDECRYPT, AESENCRYPT, and AES128ECB with no underscores; corrected to AES_DECRYPT, AES_ENCRYPT, and AES_128_ECB.
• murmur-hash3-32.md — a Note bullet was written as -Note: with no space after the dash and the sentence ended with a full-width 。; corrected to - Note: and an ASCII period.

Test plan

• CI doc build passes
• Spot-check the affected pages render correctly (error messages, MySQL references, result-table alignment, the week.md mode table no longer rendered as code, link labels)