binman: Tidy up underscores in entry documentation

Several entries currently use an underscore in the entry-type name, but in
fact a hyphen is used. Update the docs to fix this as it might be
confusing.

Also simplify the 'filename' comment and fix the 'operation' typo.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/README.entries b/tools/binman/README.entries
index 7cca030..3fbc06d 100644
--- a/tools/binman/README.entries
+++ b/tools/binman/README.entries
@@ -39,7 +39,7 @@
 
 This entry reads data from a file and places it in the entry. The
 default filename is often specified specified by the subclass. See for
-example the 'u_boot' entry which provides the filename 'u-boot.bin'.
+example the 'u-boot' entry which provides the filename 'u-boot.bin'.
 
 If compression is enabled, an extra 'uncomp-size' property is written to
 the node (if enabled with -u) which provides the uncompressed size of the
@@ -840,7 +840,7 @@
 
 This is the U-Boot binary, containing relocation information to allow it
 to relocate itself at runtime. The binary typically includes a device tree
-blob at the end of it. Use u_boot_nodtb if you want to package the device
+blob at the end of it. Use u-boot-nodtb if you want to package the device
 tree separately.
 
 U-Boot can access binman symbols at runtime. See:
@@ -876,9 +876,9 @@
 this process. This entry provides the U-Boot device-tree file, which
 contains the microcode. If the microcode is not being collated into one
 place then the offset and size of the microcode is recorded by this entry,
-for use by u_boot_with_ucode_ptr. If it is being collated, then this
+for use by u-boot-with-ucode_ptr. If it is being collated, then this
 entry deletes the microcode from the device tree (to save space) and makes
-it available to u_boot_ucode.
+it available to u-boot-ucode.
 
 
 
@@ -920,12 +920,12 @@
 --------------------------------------------------------------------
 
 Properties / Entry arguments:
-    - filename: Filename of u-boot.bin (default 'u-boot-nodtb.bin')
+    - filename: Filename to include (default 'u-boot-nodtb.bin')
 
 This is the U-Boot binary, containing relocation information to allow it
 to relocate itself at runtime. It does not include a device tree blob at
-the end of it so normally cannot work without it. You can add a u_boot_dtb
-entry after this one, or use a u_boot entry instead (which contains both
+the end of it so normally cannot work without it. You can add a u-boot-dtb
+entry after this one, or use a u-boot entry instead (which contains both
 U-Boot and the device tree).
 
 
@@ -1000,13 +1000,12 @@
 ----------------------------------------------------------------
 
 Properties / Entry arguments:
-    - filename: Filename of spl/u-boot-spl-nodtb.bin (default
-        'spl/u-boot-spl-nodtb.bin')
+    - filename: Filename to include (default 'spl/u-boot-spl-nodtb.bin')
 
 This is the U-Boot SPL binary, It does not include a device tree blob at
 the end of it so may not be able to work without it, assuming SPL needs
-a device tree to operation on your platform. You can add a u_boot_spl_dtb
-entry after this one, or use a u_boot_spl entry instead (which contains
+a device tree to operate on your platform. You can add a u-boot-spl-dtb
+entry after this one, or use a u-boot-spl entry instead (which contains
 both SPL and the device tree).
 
 
@@ -1148,7 +1147,7 @@
 See Entry_u_boot_ucode for full details of the three entries involved in
 this process. This entry updates U-Boot with the offset and size of the
 microcode, to allow early x86 boot code to find it without doing anything
-complicated. Otherwise it is the same as the u_boot entry.
+complicated. Otherwise it is the same as the u-boot entry.