Update headings to use sentence case.

pkg/docgen/README.md

Index: pkg/docgen/README.md
diff --git a/pkg/docgen/README.md b/pkg/docgen/README.md
index 66d0a4639d7a681d20f63c87758265e2c5fb4c67..343d9c0937cfcadf4c6399a28c2e9cfecb14aa41 100644
--- a/pkg/docgen/README.md
+++ b/pkg/docgen/README.md
@@ -8,7 +8,7 @@ for all `.dart` file it finds as YAML or JSON files. This outputs information
 about all classes, variables, functions, and methods defined in the library and 
 its imported libraries.
 
-### Generating Files & Uploading to Cloud Storage
+### Generating files & uploading to Cloud Storage
 
 The viewer uses YAML files generated by the docgen package as the data 
 being displayed. These files are stored in Google Cloud Storage.
@@ -20,7 +20,7 @@ These tasks can be done separately if necessary:
 
 ##### 
 
-#### Generating YAML Files
+#### Generating YAML files
 
 YAML files can be generated using the docgen package in the dart repository. 
 
@@ -44,7 +44,7 @@ library_list.json ignoring the flag.
 for the outputted documentation.
 
 
-###### Output Directory
+###### Output directory
 Documented libraries will be located at bin/docs in either YAML or JSON format 
 depending on options specified. There will also be a library_list.json, 
 containing a list of all the libraries inside the docs folder. 
@@ -68,7 +68,7 @@ layout. Follow this convention and update a new VERSION file when uploading
 a new version of documentation. You can see the format of the VERSION file 
 by running `python gsutil cat gs://dartlang-docgen/VERSION`.
 
-### Viewing Generated Documentation
+### Viewing generated documentation
 
 Docgen's generated YAML files can be used by the 
 [Dart Documentation Viewer][dartdoc-viewer] for easy viewing and navigation