Adjust includes to use <> instead of "", consistent with quickstart pages.

Right now, gtest documentation uses different #include syntax. The quickstart
pages (e.g., http://google.github.io/googletest/quickstart-bazel.html#create-and-run-a-binary) are checked in with `#include <gtest/gtest.h>` However, other
documentation (such as the primer) uses `#include "gtest/gtest.h"` (e.g.,
https://google.github.io/googletest/primer.html#writing-the-main-function).

PiperOrigin-RevId: 551878641
Change-Id: Iab93cc1da3ef4870a07b624071b75d6e9d3568c1

Author: Abseil Team

docs/gmock_cheat_sheet.md

@@ -20,7 +20,7 @@ class Foo {
 (note that `~Foo()` **must** be virtual) we can define its mock as
 
 ```cpp
-#include "gmock/gmock.h"
+#include <gmock/gmock.h>
 
 class MockFoo : public Foo {
  public:

docs/gmock_cook_book.md

@@ -3194,7 +3194,7 @@ You can unlock this power by running your test with the `--gmock_verbose=info`
 flag. For example, given the test program:
 
 ```cpp
-#include "gmock/gmock.h"
+#include <gmock/gmock.h>
 
 using ::testing::_;
 using ::testing::HasSubstr;

docs/gmock_for_dummies.md

@@ -164,7 +164,7 @@ follow:
 After the process, you should have something like:
 
 ```cpp
-#include "gmock/gmock.h"  // Brings in gMock.
+#include <gmock/gmock.h>  // Brings in gMock.
 
 class MockTurtle : public Turtle {
  public:
@@ -224,8 +224,8 @@ Here's an example:
 
 ```cpp
 #include "path/to/mock-turtle.h"
-#include "gmock/gmock.h"
-#include "gtest/gtest.h"
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
 
 using ::testing::AtLeast;                         // #1
 

docs/primer.md

@@ -395,7 +395,7 @@ You can start from this boilerplate:
 ```c++
 #include "this/package/foo.h"
 
-#include "gtest/gtest.h"
+#include <gtest/gtest.h>
 
 namespace my {
 namespace project {

docs/reference/assertions.md

@@ -88,7 +88,7 @@ For example, the following code verifies that the string `value1` starts with
 10:
 
 ```cpp
-#include "gmock/gmock.h"
+#include <gmock/gmock.h>
 
 using ::testing::AllOf;
 using ::testing::Gt;

googletest/README.md

@@ -145,7 +145,7 @@ We list the most frequently used macros below. For a complete list, see file
 ### Multi-threaded Tests
 
 GoogleTest is thread-safe where the pthread library is available. After
-`#include "gtest/gtest.h"`, you can check the
+`#include <gtest/gtest.h>`, you can check the
 `GTEST_IS_THREADSAFE` macro to see whether this is the case (yes if the macro is
 `#defined` to 1, no if it's undefined.).