docs(book): 📝 added docs on header modification

arctic-hen7 · arctic-hen7 · commit bca6430ca0ab · 2021-09-25T12:00:41.000+10:00
diff --git a/docs/0.2.x/src/SUMMARY.md b/docs/0.2.x/src/SUMMARY.md
@@ -12,6 +12,7 @@
 - [Debugging](./debugging.md)
 - [Templates and Routing](./templates/intro.md)
 	- [Modifying the `<head>`](./templates/metadata-modification.md)
+	- [Modifying HTTP Headers](./templates/setting-headers.md)
 - [Error Pages](./error-pages.md)
 - [Static Content](./static-content.md)
 - [Internationalization](./i18n/intro.md)
diff --git a/docs/0.2.x/src/templates/setting-headers.md b/docs/0.2.x/src/templates/setting-headers.md
@@ -0,0 +1,11 @@
+# Modifying HTTP Headers
+
+Most of the time, you shouldn't need to touch the HTTP headers of your Perseus templates, but sometimes you will need to. A particular example of this is if you want your users' browsers to only cache a page for a certain amount of time (the default for Perseus if five minutes), then you'd need to set the [`Cache-Control`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control) header.
+
+Perseus supports inserting arbitrary HTTP headers for any response from the server that successfully returns a page generated from the template those headers are defined for. You can do this like so (taken from [here](https://github.com/arctic-hen7/perseus/blob/main/examples/basic/src/templates/index.rs)):
+
+```rust,no_run,no_playground
+{{#include ../../../../examples/basic/src/templates/index.rs}}
+```
+
+Of note here is the `set_headers_fn` function, which returns a `HeaderMap`. This is then used on the template with `.set_headers_fn()`. Note that the function you provide will be given the state as an argument (ignored here), and you must return some headers (you can't return an error).
diff --git a/docs/next/src/SUMMARY.md b/docs/next/src/SUMMARY.md
@@ -12,6 +12,7 @@
 - [Debugging](./debugging.md)
 - [Templates and Routing](./templates/intro.md)
 	- [Modifying the `<head>`](./templates/metadata-modification.md)
+	- [Modifying HTTP Headers](./templates/setting-headers.md)
 - [Error Pages](./error-pages.md)
 - [Static Content](./static-content.md)
 - [Internationalization](./i18n/intro.md)
diff --git a/docs/next/src/templates/setting-headers.md b/docs/next/src/templates/setting-headers.md
@@ -0,0 +1,11 @@
+# Modifying HTTP Headers
+
+Most of the time, you shouldn't need to touch the HTTP headers of your Perseus templates, but sometimes you will need to. A particular example of this is if you want your users' browsers to only cache a page for a certain amount of time (the default for Perseus if five minutes), then you'd need to set the [`Cache-Control`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control) header.
+
+Perseus supports inserting arbitrary HTTP headers for any response from the server that successfully returns a page generated from the template those headers are defined for. You can do this like so (taken from [here](https://github.com/arctic-hen7/perseus/blob/main/examples/basic/src/templates/index.rs)):
+
+```rust,no_run,no_playground
+{{#include ../../../../examples/basic/src/templates/index.rs}}
+```
+
+Of note here is the `set_headers_fn` function, which returns a `HeaderMap`. This is then used on the template with `.set_headers_fn()`. Note that the function you provide will be given the state as an argument (ignored here), and you must return some headers (you can't return an error).
