fix #544: Add Loading tag to Loaders

src/_icons/fidget-spinner.svg

@@ -1,5 +1,5 @@
 ---
-tags: [toy, spinning, gadget, kids, children]
+tags: [toy, spinning, gadget, kids, children, loader, loading]
 version: "1.58"
 unicode: "f068"
 ---

src/_icons/loader-2.svg

@@ -1,5 +1,5 @@
 ---
-tags: [process, download, upload]
+tags: [process, download, upload, loader, loading]
 category: System
 version: "1.72"
 unicode: "f226"

src/_icons/loader-3.svg

@@ -1,5 +1,5 @@
 ---
-tags: [process, download, upload]
+tags: [process, download, upload, loader, loading]
 version: "1.102"
 unicode: "f513"
 ---

src/_icons/loader-quarter.svg

@@ -1,5 +1,5 @@
 ---
-tags: [process, download, upload]
+tags: [process, download, upload, loader, loading]
 category: System
 version: "1.17"
 unicode: "eca2"

src/_icons/loader.svg

@@ -1,5 +1,5 @@
 ---
-tags: [process, download, upload]
+tags: [process, download, upload, loader, loading]
 category: System
 version: "1.17"
 unicode: "eca3"