Mention pdfium_all target in README.md.

Also give an example out directory name and fix a typo.

Change-Id: I2d7532ea8c5fcdbd3502fbafcc07fb59dfafe81c
Reviewed-on: https://pdfium-review.googlesource.com/4878
Commit-Queue: Lei Zhang <thestig@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
diff --git a/README.md b/README.md
index 1f2b923..c1b57c9 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,7 @@
 
 Configuration is done by executing `gn args <directory>` to configure the build.
 This will launch an editor in which you can set the following arguments.
+A typical `<directory>` name is `out/Debug`.
 
 ```
 use_goma = true  # Googlers only.
@@ -100,9 +101,9 @@
 
 ## Building the code
 
-You can build the sample program by:
-`ninja -C <directory>/pdfium_test` You can build the entire product (which
-includes a few unit tests) by: `ninja -C <directory>`.
+You can build the sample program by running: `ninja -C <directory> pdfium_test`
+You can build the entire product (which includes a few unit tests) by running:
+`ninja -C <directory> pdfium_all`.
 
 ## Running the sample program