update man page

Closes Homebrew/homebrew#41736.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/manpages/brew.1.md

@@ -395,6 +395,13 @@ Note that these flags should only appear after a command.
     See the docs for examples of using the JSON:
     <https://github.com/Homebrew/homebrew/blob/master/share/doc/homebrew/Querying-Brew.md>
 
+  * `tap-pin` <tap>:
+    Pin <tap>, prioritizing its formulae over core when formula names are supplied
+    by the user. See also `tap-unpin`.
+
+  * `tap-unpin` <tap>:
+    Unpin <tap> so its formulae are no longer prioritized. See also `tap-pin`.
+
   * `test` [--devel|--HEAD] [--debug] <formula>:
     A few formulae provide a test method. `brew test <formula>` runs this
     test method. There is no standard output or return code, but it should

share/man/man1/brew.1

@@ -379,6 +379,12 @@ Pass \fB\-\-installed\fR to get information on installed taps\.
 See the docs for examples of using the JSON: \fIhttps://github\.com/Homebrew/homebrew/blob/master/share/doc/homebrew/Querying\-Brew\.md\fR
 .
 .IP "\(bu" 4
+\fBtap\-pin\fR \fItap\fR: Pin \fItap\fR, prioritizing its formulae over core when formula names are supplied by the user\. See also \fBtap\-unpin\fR\.
+.
+.IP "\(bu" 4
+\fBtap\-unpin\fR \fItap\fR: Unpin \fItap\fR so its formulae are no longer prioritized\. See also \fBtap\-pin\fR\.
+.
+.IP "\(bu" 4
 \fBtest\fR [\-\-devel|\-\-HEAD] [\-\-debug] \fIformula\fR: A few formulae provide a test method\. \fBbrew test <formula>\fR runs this test method\. There is no standard output or return code, but it should generally indicate to the user if something is wrong with the installed formula\.
 .
 .IP