Add "See also" sections to regex function docstrings

[AnkitaVekariya]

Description:
This PR adds "See also" sections to the docstrings of various regex functions to improve documentation navigation. The goal is to help users easily find related functions when working with regular expressions in Julia.

Fixes #56752

Changes:

• Added See also references in the docstrings of the following functions:
  • startswith
  • endswith
  • match
  • eachmatch
  • findall
  • count

These references link related functions such as occursin, replace, findfirst, and findnext to provide a more cohesive understanding of how to work with regex operations in Julia.

[tecosaur]

To me, "Also, see X for reasons, Y for other reasons" would read better. I consider "See also" to be rather specific to the citation-y list of items form, such as:

• "See also X and Y"
• "See also: X, Y, Z"
• "See also X (because reasons)"
• "foo bar (See also baz)"

[AnkitaVekariya]

To me, "Also, see X for reasons, Y for other reasons" would read better. I consider "See also" to be rather specific to the citation-y list of items form, such as:

• "See also X and Y"
• "See also: X, Y, Z"
• "See also X (because reasons)"
• "foo bar (See also baz)"

Thank you for the thoughtful feedback! I really appreciate the suggestions on improving the "See also" sections. I've updated the docstrings based on your advice, aiming to make them more readable and concise while providing better context for the related functions. Here’s an example of the updated format:

See also

• match: to find the first match of a regular expression.
• eachmatch: to iterate over all matches of a regular expression.
• findall: to locate all indices of matches in a string.

[tecosaur]

"See also:" then a list is stylistically good I think 👍, no need to make it a heading though.