Add help for meson install to the man page.

The added help text was derived from the output of the meson help
command much like the markdown online help is derived.
diff --git a/man/meson.1 b/man/meson.1
index 5e63c81..919f454 100644
--- a/man/meson.1
+++ b/man/meson.1
@@ -118,6 +118,58 @@
 \fB\-\-no\-tests\fR
 Do not build and test generated packages.
 
+.SH The install command
+
+.B meson install
+installs the project.
+
+.B meson install [
+.I options
+.B ]
+
+.SS "options:"
+
+.TP
+\fB\-h, \-\-help\fR
+show this help message and exit
+
+.TP
+\fB\-C WD\fR
+directory to cd into before running
+
+.TP
+\fB\-\-no-rebuild\fR
+Do not rebuild before installing.
+
+.TP
+\fB\-\-only\-changed\fR
+Only overwrite files that are older than the copied file.
+
+.TP
+\fB\-\-quiet\fR
+Do not print every file that was installed.
+
+.TP
+\fB\-\-destdir DESTDIR\fR
+Sets or overrides DESTDIR environment.  (Since 0.57.0)
+
+.TP
+\fB\-\-dry\-run, \-n\fR
+Doesn't actually install, but print logs. (Since 0.57.0)
+
+.TP
+\fB\-\-skip\-subprojects [SKIP_SUBPROJECTS]\fR
+Do not install files from given subprojects. (Since 0.58.0)
+
+.TP
+\fB\-\-tags TAGS\fR
+Install only targets having one of the given tags. (Since 0.60.0)
+
+.TP
+\fB\-\-strip\fR
+Strip targets even if strip option was not set during
+configure. (Since 0.62.0)
+
 .SH The introspect command
 
 Meson introspect is a command designed to make it simple to  integrate with