docs: fix the docs for install_subdir's strip_directory [skip ci]
When set to **true** only the last component is used. And throw in two minor
grammatical fixes while we're there.
@@ -1076,7 +1076,7 @@ The following keyword arguments are supported:
- `install_mode`: the file mode in symbolic format and optionally
the owner/uid and group/gid for the installed files. *(Added 0.47.0)*
- `strip_directory`: install directory contents. `strip_directory=false` by default.
- If `strip_directory=false` only last component of source path is used.
+ If `strip_directory=true` only the last component of the source path is used.
Since 0.45.0
For a given directory `foo`:
