Emacs Calc Info Appendix - 'P (in number)' should be lower cased

[David Ringo]

Hello,

I was poking through Appendix E of the Calc info manual and found a small error in the documentation. The 'P' key (i.e. Shift+p) is described as producing an error form with '+/-'.  For me this inserts pi, while lowercase 'p' triggers the '+/-' operation.  Section 5.11 describes this properly.

In case it's relevant, I'm using Emacs 26.1 on Linux Mint, from Kevin Kelley's PPA (https://launchpad.net/~kelleyk/+archive/ubuntu/emacs), but it looks like the typo is still there in master as of today:

https://git.savannah.gnu.org/cgit/emacs.git/tree/doc/misc/calc.texi#n35835

Sorry I'm not taking advantage of M-x report-calc-bug.  Email in Emacs is still foreign to me.

Hope this is useful.

- David