Minor fixes to beta function parameters and clarifying text for gamma distribution

[mikegilchrist]

Submission Checklist

• [ ] Builds locally -- see below
• [x ] New functions marked with `r since("VERSION")`
• [x ] Declare copyright holder and open-source license: see below

Summary

Minor improvements and fixes to documentation.

Note I get tex build errors which seem unrelated to my changes

$ ./build.py 2 32 render functions-reference as pdf output file: stan_docs/docs/2_32/functions-reference-2_32.pdf render functions-reference as html output dir: stan_docs/docs/2_32/functions-reference render reference-manual as pdf output file: stan_docs/docs/2_32/reference-manual-2_32.pdf render reference-manual as html output dir: stan_docs/docs/2_32/reference-manual render stan-users-guide as pdf Command Rscript -e "bookdown::render_book('index.Rmd', output_format='bookdown::pdf_book')" failed processing file: _main.Rmd output file: _main.knit.md ! TeX capacity exceeded, sorry [input stack size=10000]. \font@name -> \T1/bch/b/n/17.28 l.16293 ...org/wiki/Amdahl\textquotesingle{}s_law} {Amdahl's Error: LaTeX failed to compile _main.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See _main.log for more info. Execution halted Traceback (most recent call last): File "stan_docs/./build.py", line 129, in main() File "stan_docs/./build.py", line 125, in main make_docs(docspath, stan_version, doc, formats) File "stan_docs/./build.py", line 56, in make_docs shexec(command) File "stan_docs/./build.py", line 36, in shexec raise Exception(ret.returncode) Exception: 1

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company): Michael Gilchrist

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC BY-ND 4.0 (https://creativecommons.org/licenses/by-nd/4.0/)

[avehtari]

@bob-carpenter were you going to do something more for this?

[bob-carpenter]

Does this need a more formal review? It has a conflict now that needs to be resolved. Happy to review after that.